Chemistry Midterm Study Guide – Flashcards
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What branch of science holds the organizing principles for all of nature?
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Chemistry
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What is inorganic chemistry?
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The study of matter not containing carbon
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What is organic chemistry?
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The study of matter containing carbon
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What is biochemistry?
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The study of chemical processes that take place in organisms
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What is physical chemistry?
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The area of chemistry that deals with the mechanism, rate, and energy transfer that occurs when matter undergoes a change
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What is analytical chemistry?
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The area of study that focuses on the composition of matter
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What is applied chemistry?
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Chemical research directed at a goal or discovery that will benefit the human race
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What is pure chemistry?
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The pursuit of chemical knowledge for its own sake
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What is matter?
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Anything that takes up space
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What does matter make up?
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The universe
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What is chemistry?
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The study of the composition and changes of matter
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What is mass?
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The measure of the amount of matter an object contains
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What is mass measured with?
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Grams
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What is volume?
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The amount of space an object takes up
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What is volume measured with?
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Liters
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What is an extensive property?
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A property which depends on the amount of matter in a sample
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What are examples of extensive properties?
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Mass and volume
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What is an intensive property?
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A property that does not depend on the amount of matter in a sample
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What are examples of intensive properties?
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Malleability, ductility, conductivity
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What is a substance?
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Matter with a uniform and definite composition
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What are examples of a substance?
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NaCl, He
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What is a physical property?
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A property that does not depend on the amount of matter in a sample; same as intensive property
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What are the three (four) states of matter?
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Solid, liquid, gas (and plasma)
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What is a vapor?
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A gaseous state of a substance that is normally solid or liquid
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What is a physical change?
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A change in which some properties of matter change, but the composition remains the same
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What are the two types of physical changes?
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Reversible and irreversible
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What is a reversible change?
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A change in state; can be changed back
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What is a irreversible change?
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Crushing, splitting, or something else to a substance that cannot be undone
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What is a mixture?
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A physical blend of two or more components
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What is a phase?
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Any part of a mixture with uniform composition and properties
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What is a heterogeneous mixture?
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Two or more phases, not uniform throughout (Salad)
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What is a homogenous mixture?
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A mixture that has one phase and is uniform throughout (air)
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Differences in _____ ______ can be used to separate mixtures
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Physical properties
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Which method of separation separates a solid from a liquid?
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Filtration
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Which method of separation separates two liquids by taking advantage of different boiling points?
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Distillation
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What is an element?
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The simplest unit of matter that has a unique set of properties
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What contains two or more elements combined in a fixed proportion?
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Compound
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A _____ change produces matter of different composition from the original matter.
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Chemical
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What is a reactant?
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The substance that goes through a change in a chemical reaction
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What is a product?
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The substance formed in chemical reactions
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What is the reactant in (Sugar --> Carbon+Water)
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Sugar
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What is the product in (Sugar --> Carbon+Water)
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Carbon+Water
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Each element has a one or two letter _____ _____
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Chemical symbol
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What is the method which modern scientists use to organize the elements?
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The periodic table
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What is a horizontal row the the periodic table?
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Period
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What is a vertical column on the periodic table?
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Group
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What is the ability of a substance to undergo a specific chemical change?
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Chemical property
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What happens during a chemical reaction?
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One or more substances change into one or more new substances
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What are the four clues that indicate a chemical change?
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Transfer of energy, change in color, production of gas, and formation of a percipitate
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What does the law of conversion of mass state?
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In a chemical reaction, matter is neither created nor destroyed, just rearranged
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The mass of the reactants is always _____ to that of the products
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Equal
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What kind of quantity includes both a number and a unit?
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A measurement
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In scientific notation, the coefficient must be between ___ and ___
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1, 10
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A way of doing metric conversions, which involves the canceling of units, is _____ ______
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Dimensional analysis
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What is accuracy?
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The proximity of your measurements to the actual value
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What is precision?
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The proximity of your measurements to one another
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Which of the following is impossible? a) Good accuracy, good precision b) Poor accuracy, poor precision c) Poor accuracy, good precision d) Good accuracy, poor precision
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D) Good accuracy, poor precision
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What is accepted value?
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A value that is widely agreed upon in the scientific community
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What is experimental value?
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The value that you recorded in your own measurements
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All of the digits that can be known precisely in a number make up its _____ _____
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Significant digits
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In multiplication/division you round to the number with the least _____ _____
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Significant digits
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In addition/subtraction you round to the number with the least amount of _____ _____
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Decimal places
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10⁻¹²
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Pico- (pm)
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10⁻⁹
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Nano- (nm)
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10⁻⁶
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Micro- (µm)
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10⁻³
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Milli- (mm)
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10⁻²
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Centi- (cm)
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10⁻¹
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Deci- (dm)
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10⁰
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Unit (m)
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10¹
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Deka- (dKm)
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10²
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Hecto- (hm)
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10³
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Kilo- (km)
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10⁶
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Mega- (Mm)
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10⁹
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Giga- (Gm)
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10¹²
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Tera- (Tm)
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What is the SI unit for mass?
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Grams
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What is the SI unit for length?
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Meters
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What is the SI unit for volume?
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Liters
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1 Liter is equivalent to ______
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1 m³
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What is weight?
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The measure of the pull of gravity on a given mass
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What is temperature?
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The measure of kinetic energy
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The Celsius scale is (higher/lower) than the Kelvin scale
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273° lower
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0 K is known as _____ ______
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Absolute zero
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What is 273 K?
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Water's freezing point (32° F, 0°C)
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What is 373 K?
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Water's boiling point (212°F, 100°C)
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Mass/Volume=
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Density
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When liquids of different densities mix, what happens?
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The least dense rise, while the most dense sink
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What is absolute zero?
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The point where nothing moves, not even electrons
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Has absolute zero ever been achieved?
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No
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What is the SI measure of energy?
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Joule
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What is the SI unit of temperature?
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Kelvins
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True or false: you put a degree symbol (°) by a Kelvin measurement
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False
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What is SI an abbreviation for?
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International System of Units
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What is an atom?
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The smallest unit of an element that maintains its identity in a chemical reaction
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Who was the first person to suggest the existence of an atom?
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Democritus
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How was Democritus wrong about the atom?
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He said it was indivisible; but there are actually subatomic particles
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What are all four aspects of Dalton's Atomic Theory?
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1. All elements are composed of tiny indivisible particles called atoms 2. Atoms in a given element are identical, but differ from other elements 3. Atoms are neither created nor destroyed in a chemical reaction 4. A given compound always has the same formation and types of atoms
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Most atoms have a radii between _____
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50 and 200 nanomenters
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What are the three subatomic particles?
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Protons, neutrons, and electrons
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What is the charge or a proton?
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Positive
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What is the charge of an electron?
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Negative
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What is the charge of a neutron?
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No charge, neutral
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Who discovered electrons?
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J.J. Thompson
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How did J.J. Thompson discover electrons?
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He used the Cathode Ray
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Describe the Cathode Ray experiment.
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Thompson sealed low pressure gases within glass tubes fitted with metal electrodes. The result was a glowing beam flowing from the cathode to the anode. He knew that like charges repel and opposite attract, so he hypothesized that the glowing beam was full of tiny, fast moving, negatively charged particles
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What charge does a Cathode have?
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Negative
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What charge does an anode have?
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Positive
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What model of an atom did J.J. Thompson propose?
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Plum-pudding model
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Describe the Plum-pudding model.
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Electrons were stuck in positively charged material, like raisins in dough
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What is the mass of an electron?
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1/1840 amu
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Who discovered the proton?
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Eugene Goldstein
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Who discovered the neutron?
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James Chadwick
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Who performed the Gold-Foil experiment?
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Ernest Rutherford
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Describe the Gold Foil experiment.
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Rutherford aimed a beam of alpha particles at a piece of gold foil surrounded by a fluorescent screen. He expected the particles to be absorbed, since the accepted atom model at the time was the plum pudding model. However, none of the particles absorbed. Most of the alpha particles went clean through the foil, some were deflected a bit, and some were drastically deflected.
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Describe Rutherford's atomic model.
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The atom is mostly empty space. There is a tiny central core composed of protons and neutrons, while electrons are distributed around the nucleus and occupy most of the volume.
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True/False: Rutherford's atomic model is the modern belief.
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True
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What is Rutherford's atomic model also called?
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The nuclear atom
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What are alpha particles?
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Helium atoms with no electrons (He²+
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What makes one element differ from another?
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The number of protons
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What is the atomic number?
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The number of protons in the nucleus of an atom (H=1, Hg= 79)
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What is the mass number?
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The number of protons and neutrons in the nucleus of an atom (C-12=6p,6n)
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What is an isotope?
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An atom that has a regular number of protons but an irregular number of neutrons
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What is the atomic mass of an element?
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The weighted average mass number of all the isotopes of a certain element
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Example of the atomic mass.
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Cl - 35 x 75.77% (.7577) = 26.5195 AMU Cl - 37 x 24.23% (.2423) = +8.9651 AMU ANSWER= 35.4846 AMU
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What is an atomic mass unit?
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A single unit which describes the relative mass of a proton or neutron. 1/12 the mass of a Carbon-12 atom
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What is the standard reference isotope?
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Carbon-12
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What did Bohr propose concerning electrons in an atom?
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Electrons could only be found in specific paths around the nucleus.
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What is an energy level?
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The specific energies an electron can have
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What is a quantum?
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The amount of energy required to move an electron from one energy level to the next
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The higher the energy level occupied by an electron, the ____ energy it takes to move to the next energy level.
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Less
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What is the atomic model in use today?
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The Quantum Mechanical Model
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What does the Quantum Mechanical Model describe?
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The mathematical probability of finding an electron at a certain point around the nucleus and the behavior of electrons in an atom
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Describe electron density.
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Higher electron density is close to the nucleus. Lower electron density is farther away from the nucleus. This is represented by an electron cloud.
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What is an atomic orbital?
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A region of space where there is a higher probability of finding an electron
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Each sublevel corresponds to an ______ shape.
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Orbital
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What is the shape of the S sublevel?
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Spherical
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What is the shape of the P sublevel?
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Dumbell
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What is the shape of the D sublevel?
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Flower
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What is the shape of the F sublevel?
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Undefined, too hard to explain
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What is an electron configuration?
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The way that electrons are arranged in the various orbitals around the atom
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What is the order of the sublevels?
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1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f,6p,7p
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What is the maximum amount of electrons in the S sublevel?
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2 (1 orbital)
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What is maximum amount of electrons in the P sublevel?
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6 (3 sublevels)
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What is the maximum amount of electrons in the D sublevel?
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10 (5 sublevels)
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What is the maximum amount of electrons in the F sublevel?
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14 (7 orbitals)
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What are the three major rules regarding electron configuration?
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The Aufbau Principle, The Pauli Exclusion Principle, and Hund's Rule (Filling the Bus rule)
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What is the Aufbau Principle?
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Electrons occupy the orbitals of lowest energy first
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What is the Pauli Exclusion Principle?
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Up to two electrons can occupy an orbital, and they each spin opposite directions
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What is Hund's Rule?
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Electrons occupy orbitals in a way so that the number of electrons with the same spin is as large as possible (Filling the Bus Rule)
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What is the basis for Exceptional Electron Configurations?
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Since the most stable electron configurations are half-filled or completely filled (3d⁵ or 3d¹⁰) an electron may be given to another level or sublevel in order to reach this configuration. (4s²,3d⁹→4s¹,3d¹⁰)
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What is wavelength?
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The distance between any two corresponding points on a lave
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What sign represents wavelength?
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Lambda (λ)
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What is amplitude?
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A waves' height from zero to crest
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What is crest?
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The highest point on a wave
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What is frequency?
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The number of complete waves cycles per a unit of time
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What sign represents frequency?
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Nu (v)
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What is a full wave cycle?
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A wave starts at the zero, reaches its highest point, goes past zero to its lowest point, and reaches back to zero
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What is a hertz?
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A unit used to represent frequency (a reciprocal second (/s or s⁻¹))
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What does λ * v always equal? (Wavelength * Frequency)
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(C) The Constant
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What is the constant?
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The Speed of Light
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What is the speed of light?
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3.0*10⁸m/s (Therefore, λ * v always equals 3.0*10⁸m/s)
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What is electromagnetic radiation?
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Energy waves that travel at a constant; includes all light and rays (gamma, x, ect.)
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When frequency increases, wavelength ______.
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Decreases
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Frequency and wavelength are ______ _______ to each other
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Inversely proportional
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List the electromagnetic waves from smallest to largest frequency.
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Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
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Mnemonic device to memorize electromagnetic waves from smallest to largest frequency
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(R)otten (M)en (I)nevitably (V)isit (U)gly (X)-(G)irlfriends
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List the visible colors from smallest to largest frequency.
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Red, orange, yellow, green, blue, indigo, violet
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What do electrons do when atoms absorb energy?
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Jump a quantum
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What is the atomic emission spectrum?
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The pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains
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What is a photon?
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A quantum of light
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What is Planck's constant?
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6.63*10⁻³⁴ Js
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What does Planck's constant describe?
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It is used in an equation to describe photon energy (E=hv)
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What is photoelectric effect?
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The ejection of electrons by certain metals when it absorbs light above a threshold frequency. It basically states why light reflects off of metal.
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What is the difference between ground state and excited state?
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In ground state, electrons are on the lowest possible energy levels. In excited state, electrons have already jumped a quantum or higher.
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What is the light emitted by an electron changing energy levels directly proportional to?
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The energy change of an electron
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What does the Heisenberg Uncertainty Principle state?
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it is impossible to know both the velocity and the exact position of a particle at the same time because by finding one, you tamper with the other
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Louis be Broglie discovered that matter behaves like _____ because....
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Matter behaves like light because it moves like waves
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The smaller the particle, the _____ the wavelength.
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Bigger
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What did early chemists use to group the elements?
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Properties
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How did Dobereiner group the elements?
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He grouped them into triads based on properties, such as Chlorine, Bromine, and Iodine
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How did Dmitri Mendeleev organize the elements?
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By increasing atomic mass
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What astonishing feat did Mendeleev accomplish with his table?
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He predicted the properties of undiscovered elements
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With what two elements did Mendeleev break the order of his table?
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Tellurium and Iodine
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Why did Mendeleev break the order of his table?
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He knew iodine should be adjacent to Bromine and Chlorine on the table based upon properties
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How are elements arranged on the modern periodic table?
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By increasing atomic number
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What is a group on the periodic table?
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Columns
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What is a period on the periodic table?
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Row
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What is a family on the periodic table?
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Another name for groups
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How many periods are on the periodic table?
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7
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How many groups are on the periodic table?
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18
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What does the number of elements per period pertain to?
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The possible number of electrons in the highest principle energy level.
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Explain periodic law.
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When the elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties. Therefore elements with similar properties end up in the same groups
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What are the three classes of elements?
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Metals, metalloids, and nonmetals
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Why are some elements in periods 6 and 7 placed below the table?
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To make the table more compact
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What happens as you go from left to right on a period in terms of class?
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Elements become less metal and more nonmetal
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What is special about the electron configurations of representative elements?
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The number of valence electrons indicates the group number
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Describe the properties of metals.
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Good conductors, shiny, mostly solid, no gases, malleable, ductile, not brittle
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Describe the properties of nonmetals.
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Poor conductors, not shiny, few solids, mostly gases, not malleable, not ductile, brittle
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Describe the properties of metalloids.
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Sometimes good conductors, sometimes shiny, all solids, sometimes malleable, sometimes ductile, sometimes brittle
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What are the alkaline earth metals known for?
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They are so reactive that they are never found unbonded in nature
