midterm review sheet – Flashcards

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Define Chemistry
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Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes.
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If you were studying properties of diamonds (diamonds are made of carbon), you would be studying ______ chemistry.
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organic
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If you were studying how the intake of potassium affects the production of ATP, you would be studying ______ chemistry.
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biochemistry
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If you were studying the energy given off by a combustion reaction, you would be studying _____ chemistry.
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physical
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If you were studying how oxygen binds to hemoglobin (contains iron), you would be studying __________ chemistry.
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inorganic
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If you were studying the composition of wool to determine how to make clothes softer, you would be studying _______ chemistry.
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analytical
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If you used computers to put together a model that showed the destruction of the ozone layer, you would be studying _________ chemistry.
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theoretical
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Use the definitions of basic research and applied research to distinguish the two terms.
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Basic research is carried out for the sake of increasing knowledge, such as how or why a specific reaction occurs and what the properties of a substance are. On the other hand, applied research is generally carried out to solve a problem.
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What is the benefit of technological development? Name one example of technological development in our society.
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The benefit is that it improves the quality of our lives. EX: biodegradable materials, computers, air conditioning
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Define matter. Define mass.
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Matter- anything that has mass and takes up space.
Mass- a measure of the amount of matter.
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What are the four basic building blocks of matter?
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atom, element, compound, molecule
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Define element.
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element- a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom.
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Define atom
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the smallest unit of an element that maintains the chemical properties of that element.
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What are extensive properties? Give one example
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Extensive properties depend on the amount of matter present.
EX: volume, mass, amount of energy in a substance
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What are intensive properties? Give an example.
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Intensive properties do not depend on the amount of matter present.
EX: melting point, boiling point, density, color, texture, hardness
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Four physical properties of a classroom desk.
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1) three feet off the ground
2) tan colored
3) solid
4) flat surface
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What are three physical changes involved in cooking?
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1) cutting
2) melting
3) boiling
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List two changes of state. Are changes of state classified as physical or chemical changes?
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1) melting
2) boiling
Changes of state are classified as physical changes.
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Solids have a _________ volume and __________ shape.
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Solids have a definite volume and a definite shape.
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Liquids have a ______ volume and _________ shape.
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Liquids have a definite volume and an indefinite shape.
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Gases have a ______ volume and _______ shape.
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Gasses have an indefinite volume and an indefinite shape.
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What is the main difference between a physical property and a chemical property?
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A physical property is a characteristic that can be observed or measured without changing the identity of the substance, whereas a chemical property relates to a substances ability to undergo changes that transform it into different substances. Physical properties can be observed without changing the identity of the substance, chemical properties can not.
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List three chemical changes involved in cooking
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baking chicken, grilling hamburgers, frying shrimp
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Chemical changes involve reactants and products. What is the difference between these two terms.
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Chemical changes begin with reactants which turn into products
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The law of conservation of mass states that the mass of the _______ must equal the mass of the _______.
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The law of conservation of mass states that the mass of the reactants must equal the mass of the products.
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Matter can be divided into two categories. What are they?
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1) pure substances
2) mixtures
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What is the difference between a homogeneous mixture and a heterogeneous mixture? Give an example of each.
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homogeneous is consistent throughout (sweet tea)
heterogeneous is not consistent throughout (salsa)
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An _________ like lithium or a ________ like salt can both be considered pure substances.
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An element like lithium or a compound like salt can both be considered pure substances
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A compound can be broken down into elements by what kind of change?
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a chemical change
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Horizontal rows on the periodic table are called _________.
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periods
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Vertical columns on the periodic table are called _________.
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groups
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What is the scientific method?
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A logical approach to solving problems
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List the four steps to the scientific method.
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observe, hypothesize, experiment, conclude
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There are two types of data. What are they? How can you tell the difference between the two?
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1) qualitative - data that deals with descriptive information
2) quantitative- data that deals with numerical information
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When testing a hypothesis the experimenter should use controls, why?
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To have a way to compare the results of your experiment
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Use the definition of dependent variable and independent variable to distinguish the two terms.
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dependent variable- the variable that changes because of the independent variable
independent variable- the variable that is changed by the scientist
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If you were to do an experiment to test to see which paper towel was the most absorbent, list three controls.
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1) amount of paper towel used
2) amount of liquid used
3) type of liquid used
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Based on the paper towel experiment, what would be the independent variable and the dependent variable?
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independent variable- paper towel brand
dependent variable- how much liquid was absorbed
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What is the next step if the hypothesis is not supported by the experiment?
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Either revise or reject the hypothesis.
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What is a theory? What is a hypothesis?
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theory- a broad generalization that is supported by many experiments

hypothesis- a testable statement
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What two things make up a measurement?
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1) number
2) unit
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The SI Units are used across the world for science. Why is it important that scientists all use the same units?
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So that scientists across the world use the same units which allows results to be shared
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List the seven SI base units.
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meter, gram, second, kelvin, mole, ampere, candela
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How are the base units manipulated to account for large and small measurements?
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prefixes are added
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How does mass differ from weight?
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mass is not dependent on gravity, weight is
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What does volume measure? List three units for volume.
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Volume measures the amount of space an object takes up.
Units for volume:
1) cm cubed
2) mL
3) L
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What is the formula for density? What is the unit for density?
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D= m/v
density = mass divided by volume.
the unit for density is g/mL or g/cm^3
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Can density be measured directly? How did we determine the density of a penny in the penny lab?
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No. In the penny lab we used a scale to find the mass, then the water displacement method to find volume. We then calculated density with the formula.
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Why does ice float in water?
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Ice has a lower density than water.
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Convert 435g to mg.
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435,000 mg
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convert 3.54 cm^3 to L.
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3.54cm^3 = 3.54mL = 0.00354 L
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What is the difference between accuracy and precision?
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accuracy- the closeness of a measurement to the accepted value
precision- the closeness of a set of measurements to each other
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Are the following test scores accurate, precise, neither or both? 74, 70, 76
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They are precise but not accurate
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What does the percent error tell you about your experiment? Is a high percentage or a low percentage a more accurate experiment?
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How close your data is to the accepted data. A low % is a more accurate experiment
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If the actual value for the density of copper is 7.34 g/mL and the value you recorded after your lab was 8.42 g/mL, what is the percent error of your experiment?
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[(accepted-experimental)/accepted]*100
[(8.42-7.34)/7.34]*100=14.7%
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How many significant figures in each of the following numbers?
a) 52.5200
b)3003
c)20300
d)3.500
e)0.00254
f)900
g)200500.0
h)8290
i)0.00520
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a)5
b)4
c)3
d)4
e)3
f)1
g)7
h)3
i)3
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Who was the first person to believe that matter was made up of smaller particles?
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Democritus
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Was Democratis supported? why or why not?
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no, there was no proof for his ideas
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Why did it take nearly 2,000 years before anyone developed these ideas of whether matter is made of smaller particles or not?
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It was not until then that there was technology that allowed proof
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State the laws of definite and multiple proportions; be able to identify both on the exam.
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law of definite proportions- a compound contains the same elements in the same proportions by mass regardless of the size or source of the compound

law of multiple proportions- if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always in a ratio of small whole numbers
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Who developed atomic theory?
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Dalton
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What is the first statement of the atomic theory?
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all matter is composed of small particles called atoms
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What are the two modifications that have been made to the atomic theory?
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1) atoms are divisible
2) not all atoms of the same element are identical
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Define atom
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the smallest particle of an element that retains the chemical properties of that element
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What are the three subatomic particles that make up the atom?
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proton, neutron, and electron
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Who discovered that subatomic particles existed by performing the cathode ray experiment?
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Thomson
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How did scientists determine that the cathode ray was composed of negatively charged particles?
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When a negative plate was put up to the glass tube, the cathode ray inside bent away from the negative charge.
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Describe the setup of Rutherford's gold foil experiment.
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Rutherford shot alpha particles at a sheet of gold foil, the experiment was surrounded by zinc sulfide which would flash if hit by the alpha particle.
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What surprised scientists when observing the gold foil experiment?
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That some of the alpha particles hit the gold foil and bounced back
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What result of the gold foil experiment proved that the atom was made mostly of empty space?
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Most of the alpha particles went straight through undisturbed.
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What result of the gold foil experiment proved that the nucleus was dense?
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Whatever caused the large alpha particle to stop and change direction must be massive, a large mass and a small volume means that the particle is dense
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What result of the gold foil experiment proved that the nucleus was positively charged?
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The positive charged alpha particles were deflected. Like charges repel one another
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What do nuclear forces do?
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They hold the nucleus together
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What two particles are located inside the nucleus?
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proton and neutron
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The number of protons in an atom can also be called the ________.
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atomic number
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Isotopes differ in two ways. What are the two ways?
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1) number of neutrons
2) mass
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Name three ways that isotopes are the same.
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1) number of protons
2) number of electrons
3) chemical behavior
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The total number of protons and neutrons can also be called the ______.
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mass number
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What does amu stand for?
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atomic mass unit
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The unit amu is based on which isotope?
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carbon-12
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Identify the mass in amus for the proton, neutron, and electron
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proton = 1 amu
neutron = 1 amu
electron = 0 amu
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List three types of electromagnetic radiation.
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gamma rays, X-rays, UV rays
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List the one thing that all waves have in common.
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They all travel at the speed of light. (3.00 *10^8 m/s)
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List three ways that waves are different.
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1) wavelength
2) frequency
3) energy
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Describe the difference between frequency and wavelength.
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wavelength- the distance between equivalent points on adjacent waves

frequency- the number of waves that pass a given point in one second
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Wavelength and frequency are related ________.
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indirectly
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Energy and frequency are related _________.
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directly
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Who first came up with the idea that energy was emitted as particles not as waves?
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Planck
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Einstein came up with the dual __________-___________ nature for electromagnetic radiation.
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dual wave-particle nature.
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What is a photon?
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a particle of electromagnetic radiation carrying a quantum of energy
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Describe how an electron moves from ground state to excited state and back to ground state.
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An electron in its lowest energy state is in its ground state, when it absorbs energy it moves to an excited state, it gives off a photon and moves back to ground state.
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What is released when an electron moves from excited state to ground state?
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a photon
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What is the difference between ground state and excited state?
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ground state- lowest energy level
excited state- higher energy level
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Each atom has its own ___________ ________________ ______________ that can be used to identify the element, much like a fingerprint.
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atomic emission spectrum
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How did Bohr describe the movement of electrons?
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moved around the nucleus in organized orbits like planets orbit around the sun
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The further the electron is away from the nucleus the ( more / less ) energy it has.
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more
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What is the difference between absorption and emission?
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absorption- taking in energy
emission- giving off energy
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What three scientists contributed to the current Quantum Model of the Atom?
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de Broglie, Heisenberg, Schrodinger
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What is predicted by the Schrodinger equation?
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the probability of finding an electron in a given orbital
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State the Heisenberg Uncertainty Principle
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The position and velocity of an electron cannot be determined simultaneously.
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What is an atomic orbital?
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a region of space where an electron is likely to be found
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How many energy levels are possible in an atom?
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7
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Each energy level contains sub levels. What are the four sub-levels and their shapes?
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1) s -sphere
2) p -dumbbell
3) d -4 leaf clover
4) f -complicated
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Each sub-level contains orbitals. How many orbitals are in each type of sub-level?
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s-1
p-3
d-5
f-7
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How many electrons are required to fill the first energy level?
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2
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How many electrons can go into the third energy level?
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18
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What information can be determined from the description 5s^2?
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electrons are located in the 5th energy level in a spherical shaped sub-level and there are 2 electrons present.
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How is a nuclear equation different from a chemical equation? (give at least two differences)
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nuclear equations- change atoms from reactant to product; give off large amounts of energy

chemical equations- atoms stay the same from reactant to product; give off small amounts of energy
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What are the main subatomic particles involved in a chemical equation?
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electrons
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What are the main subatomic particles involved in a nuclear equation?
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protons and neutrons
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Which type of reaction, chemical or nuclear, give larger releases of energy?
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nuclear
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What are the three types of radiation?
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alpha, beta, and gama
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Rank the three types of radiation from most massive to least massive.
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alpha, beta, gamma
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Rank the three types of radiation from most penetrating to least penetrating.
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gamma, beta, alpha
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How did Rutherford determine that there were three types of radiation?
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placed a positive and negative plate above and below a radioactive substance; beta was attracted to the positive plate, alpha was attracted to the negative plate, and gamma was unaffected
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What was Roentgen's contribution to nuclear chemistry?
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developed the X-ray
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What was Becquerel's contribution to nuclear chemistry?
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determined that radioactive substances spontaneously give off radiation
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What was the Curie's contribution to nuclear chemistry?
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isolated radium and plonium
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Cobalt-60 has a half-life of 5.27 years. How much of a 165g sample remains after 26.35 years?
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5.16 g
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How are fission and fusion similar?
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fission and fusion are both nuclear processes.
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How are fission and fusion different?
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fission- splitting of a large atom to release energy
fusion- joining of smaller atoms to release energy
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What are the only two fissionable isotopes?
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uranium and polonium
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How is fission a chain reaction?
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fission begins when a neutron hits an unstable uranium atom. When this reaction is complete, 3 neutrons are given off allowing the reaction to continue.
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How is the speed of the fission reaction controlled in a nuclear reactor?
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by using control rods to absorb neutrons and slow down the reaction
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The reactor heats the water which generates steam. The steam turns the _____ which generates _____.
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turbine; electricity
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What is the only substance that produces energy from fusion?
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the sun
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What are the current limitations that are keeping us from using fusion as a main power source?
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temperature required is very high; also, we have to develop a container to hold this extremely high temperature.
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What is a spent fuel rod?
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a rod that use to contain fissionable uranium atoms, but has used all the uranium
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What is done with the spent fuel rods after they are removed from the nuclear reactor?
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they are put in spent fuel pools (swimming pools)
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What are some benefits to using nuclear reactors to make energy compared to other methods?
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cheap, release no harmful gases into atmosphere, easy to do
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What are some drawbacks to using nuclear reactors to make energy compared to other methods.
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give radioactive product that must be stored, plants are expensive to build
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What is the unit used to measure the dose of radiation absorbed by humans?
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rem
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What are three methods used to detect radiation?
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film bodge, Geiger counter
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List 5 uses of nuclear chemistry.
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bombs, X-rays, cancer treatment, to make energy, smoke detectors
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______ came up with arranging the elements in order of their repeating properties. He arranged the elements in order of increasing atomic mass.
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Mendeleev
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_______ later revised the periodic table by arranging the elements in order of increasing _____ ________.
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Moseley; atomic number
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State the periodic law.
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when the elements are arranged in order of increasing atomic number their properties will repeat.
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What is the name of group 1 elements?
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Alkali metals
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What is the name of group 2 elements?
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Alkaline Earth metals
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What is the name of group 17 elements?
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Halogens
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What is the name of group 18 elements?
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Noble Gases
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What is the name of groups 3-12?
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transition metals
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What are the names of the two rows that make up the f-block?
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Lanthanides and Actinides
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What are metalloids? Where are they located on the periodic table?
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substances that have properties of both metals and nonmetals
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List three properties of metals. Where are they located on the periodic table?
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good conductors, malleable, ductile; to the left of the stair-step line
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list three properties of nonmetals. Where are they located on the periodic table?
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bad conductors, not malleable, brittle; right of the stair-step line
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List three properties of s-block metals.
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soft, very reactive, good conductors
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List two properties of p-block metals.
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harder than s-block metals, not as reactive as s-block metals
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list four properties of d-block metals.
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shinny, good conductors, hard, malleable
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Explain why group 18 is referred to as the noble gases?
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because their outer energy level is full and they do not interact (bond) with any other elements
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Explain what the atomic radius measures.
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distance from nucleus to edge of electron cloud
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How is the atomic radius of an atom actually measured?
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distance between 2 nuclei divided by 2
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What is the period trend or the atomic radius? The group trend?
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period trend= decreases to the right
group trend= increases going down
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Rank the following elements from largest radius to smallest radius: Cl, I, Br, C, F, Li
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I, Br, Cl, Li, C, F
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What is the group trend for ionic radius?
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increases as go down groups
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What is the difference between a cation and an anion? Include how each is formed.
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-cation is a positive ion that forms when electrons are lost
-anion is a negative ion that forms when electrons are gained
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What is the period trend for ionization energy? The group trend?
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period: increases to the right
group: decreases going down
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What is ionization energy?
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the energy required to remove an electron from an atom
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When an electron is removed from an element a ( cation / anion ) is formed. Are metals or nonmetals more likely to do this?
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cation; metals
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What is electronegativity?
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the attraction for electrons in a chemical bond
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What is the most electronegative element?
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fluorine
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Why do elements bond?
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to become stable
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What electrons are involved in the bonding process?
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valence electrons
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What types of elements are combined in a compound? what type of bonding? List one example of a compound.
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metal and nonmetal; ionic; NaCl
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List three properties of ionic compounds.
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high melting point, conduct when liquid, brittle
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What is the overall charge of ionic compounds?
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zero (neutral)
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How are ionic bonds formed?
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metal cation is attracted to a nonmetal anion
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Why can ionic compounds not conduct electricity in the solid state?
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because the anions are not free to move; surrounded by cations
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What is a cation? Give an example.
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an ion with a positive charge
Ex: Mg 2+
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What is an anion? Give an example?
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An ion with a negative charge.
Ex: O2-
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Why, when writing the name of a compound that contains a transition metal, does a Roman numeral have to be included?
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Because transition metals do not always form the same ion; the correct one is indicated with a Roman numeral
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What is a binary compound? All binary compounds, whether ionic or covalent, will end with what suffix?
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a combination of 2 elements; will end with -ide
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What is a polyatomic ion?
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an ion composed of more than one atom.
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What is the term used in metallic bonding that describes the fact that electrons do not belong to one particular atom?
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delocalized electrons
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Why are electrons delocalized in metals?
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because the outer energy levels overlap
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Why are metals good conductors of heat and electricity?
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because the delocalized electrons are free to move
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Why are metals shiny?
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because delocalized electrons are free to move
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What types of elements are combined in a molecule? what type of bonding? List one example of a molecule.
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nonmetal and nonmetal; covalent; CO2
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What is a diatomic molecule?
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a molecule containing 2 atoms
EX: Cl2 or CO
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Which bonds are stronger, ionic or covalent?
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ionic
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What would melt first, a block of ice or a grain of salt? Why?
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block of ice; ice is covalent and salt is ionic; because ionic is stronger than covalent, covalent will melt first
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How many electrons are shared in a single bond?
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two
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How many electrons are shared in a double bond?
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4
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How many electrons are shared in a triple bond?
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6
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Rate single, double, and triple bonds from longest to shortest. From strongest to weakest.
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longest-shortest: single, double, triple
strongest-weakest: triple, double, single
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What is the difference between a lone pair of electrons and a shared pair of electrons?
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lone pair belong only to one atom, shared pair is shared between two atoms
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State the octet rule
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each atom will lose, gain, or share to achieve 8 electrons in their outer energy level
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What are the two exceptions to the octet rule?
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Hydrogen and helium (they only want 2, not 8)
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What three things must be checked in order for a Lewis structure to be correct?
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total number of electrons, octet rule, used correct number of atoms
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Lewis structures represent molecules in 2D, in order to represent molecules in 3D what theory must be used?
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VSEPR theory
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What is the VSEPR theory?
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describes the 3D arrangement of atoms in a molecule
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When assigning variables to molecules in order to determine the VSEPR shape, what does A represent? What does B represent? what does E represent?
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A- central atom
B- atoms bonded to central atom
E- lone pairs of electrons on the central atom
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Why do the trigonal planar and bent shapes have bond angles less than 109.5??
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because more than one correct lewis structure can be drawn
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Polar bonds and nonpolar bonds are the two types of covalent bonds. How are they different? Give an example of each.
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polar bonds- electrons shared unequally (partial charges present) EX: H-F
nonpolar bonds- electrons shared equally (no partial charge present) EX: O-O
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How is an intermolecular force different from an ionic or covalent bond?
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intermolecular forces occur between molecules; intro molecular forces (ionic and covalent) occur within molecules
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List three types of intermolecular forces
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dispersion, dipole, hydrogen bonding
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How can you determine the strength of a covalent bond?
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electronegativity difference
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Hydrogen bonding occurs when hydrogen bonds to which 3 elements?
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F, O, N
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London dispersion forces exist between ________ molecules.
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all
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Dipole-dipole forces exist only between _____ molecules.
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polar
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Why are partial charges used in polar molecules?
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there is an unequal distribution of electrons
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How is it determined which atom in the bond gets the partial negative charge?
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the more electronegative atom gets the partial negative.
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