Chemistry Final Exam (First Semester) – Flashcards
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chemistry
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the study of the composition of matter and the changes that matter undergoes.
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matter
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anything that has mass or takes up space.
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the scientific method
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make an observation, create a hypothesis, experiment the hypothesis, collect data 5. Repeat experiment 6. Theory
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hypothesis
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A proposed explanation about your observations. A hypothesis is only valid if it can be tested.
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variable
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The one thing that changes during the experiment.
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point of reference
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Your control variable.
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repeated experiments
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To make sure your results are attainable again.
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scientific law
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One that summarizes the results of observations and experiments.
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law vs theory
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A law describes and occurrence without an explanation whereas theories have an explanation of the ocurrence.
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3 states of matter
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Solid, Liquid, Gas
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physical change
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a change that alters matter, but does not change its composition. Examples: bending, cutting, boiling, grinding, melting, freezing.
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mixture
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a physical blend of 2 or more substances. Two different types of mixtures: Heterogeneous→different throughout, not uniform in composition. Homogeneous→same throughout, uniform in composition.
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element
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A substance which cannot be separated into simpler substances by chemical means. Examples: Hydrogen→ (H) Lithium→ (Li) Oxygen→ (O) Flourine →(F)
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compound
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Substances that can only be separated into simpler substances by chemical means. Examples: H₂O→ 2 hydrogens & 1 oxygen can be extracted. O₂→ Oxygen gas, can be separated into 2 oxygen elements/atoms
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chemical reaction
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One or more substances change into new ones. Example: Iron + Oxygen + Water→ rust
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chemical change
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heat, smoke, steam, any energy being released, or color change, odor, solid formed.
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law of conservation of matter
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Matter can neither be created nor destroyed during a chemical reaction, only changed in form.
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qualitative measurement
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Descriptive, non numeric results. Example: The reaction turned blue.
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quantitative measurement
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results expressed numerically.
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Scientific Notation
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0.065= 6.5 x 10⁻² 32,000= 3.2 x 10⁴
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Accuracy
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How close a measurement comes to its actual value.
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Precision
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How close a series of measurements are to one another.
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Error
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Accepted value minus experimental value
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Percent Error
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| error | ÷ accepted value x 100
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Density
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D= mass÷ volume
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Density of Water
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1.0 g/cm³
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List all charged particles:
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Protons→positively charged particles= p⁺ Neutrons→neutrally charged particles= n⁰ Electrons→negatively charged particles= e⁻
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Keeps Protons from Repelling
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Strong nuclear force overcomes the electromagnetic repulsion of protons in the nucleus.
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Arrangement of Charged particles in the Nucleus/Atom
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Protons/Neutrons are located in the nucleus and →are most of the mass← Electrons are found in the electron cloud outside the nucleus outside the electron cloud →makes up most of the volume←
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Atomic Number
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the number of protons in an element
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Isotope
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Atoms of the same element that contain different numbers of neutrons.
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Mass Number
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Total # of protons/neutrons in the nucleus of a specific atom.
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What skeletal equations do not include
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the relative amounts of the reactions and products. *Skeleton=bare/nothing*
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What chemical reactions must obey
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Law of Conservation of Mass
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Information given in a chemical reaction
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states of matter, reactants, products.
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Combination Reaction
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Two or more substances combine to form a single substance. The reactants are usually 2 elements or 2 compounds. The products are always a compound.
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Decomposition Reaction
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A single compound is broken up into 2 or more products.
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Single Replacement Reaction
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One element replaces a second element in an equation. Used to determine whether a metal will replace another metal.
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Double Replacement Reaction
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Involves an exchange of positive ions between 2 reacting compounds. Usually one product will perform a precipitate or a gas or a molecular compound.
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Combustion Reaction
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An element or compound that reacts with oxygen often producing energy as heat or light. A common reactant is a hydrocarbon which includes atoms of carbon and hydrogen→CO₂ & H₂O
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What the atomic radius indicates
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The size of atoms
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The reason that atomic radius increases as you move down in a group
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Because the outer orbital is larger as you move down (increasing energy levels)
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The reason atomic radius increases as you move left
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Because nuclear charge increases and pulls the electrons closer as you move right.
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Ion
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An atom with a charge (pos or neg)
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Ionization Energy
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The energy required to move an electron from a gaseous atom (making it a positive ion)
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The reason that ionization energy decreases as you move up in a group, what is harder to remove in this case?
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The size of the atom decreases as you move up in a group making it harder to remove.
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The reason ionization energy increases as you move right
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Nucleus grows bigger which creates more positive charge which makes it harder to remove electrons.
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The charge of metallic elements
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Negative because they have to gain electrons to satisfy the octet rule.
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The charge of nonmetals
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Positive
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Cation
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Positively charged ion
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Anion
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Negatively charged ion
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Size of a cation compared to a neutral atom
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Smaller because they have lost electrons
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Size of an anion compared to a neutral atom
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Larger because they have gained electrons.
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Group trend for ionic size
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increases as you go down
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Periodic trend for ionic size
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decreases as you move to the right.
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Electronegativity
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the tendency for atoms to attract electrons from an atom of another element it is combined to.
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Group trend for electronegativity Period trend for electronegativity
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Increases as you move up Increases as you move right
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Where metals are located on the periodic table
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To the left of the staircase
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Where nonmetals are located on the periodic table
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to the right of the staircase
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Where semimetals are located on the periodic table
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on the staircase
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Group Number
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# of electrons in outermost energy level of an atom
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IA Elements
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Alkaline Metals
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IIA Elements
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Alkaline Earth Metals
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VIIA Elements
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Halogens
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VIIIA Elements
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Noble gases
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The reason noble gases are inert Definition of inert
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they do not want to react with other elements... not to participate in chemical reactions.
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Properties of ionic compounds
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Held together with strong ionic bonds electrically neutral high melting point also called salts are electrolytes
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When salts are placed in water
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The ionic compound breaks apart into ions that conduct electricity when dispersed
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The solid that ionic compounds form
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Crystalline solids made of repeating molecules, atoms, or ions. 3D pattern.
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Coordination number
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The number of ions of opposite charge that surround the ion in a crystal.
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Another name for light
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electromagnetic radiation
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How light travels
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in waves
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Bohr's Model
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Model that shows electrons arranged in orbits around the nucleus. Electrons have fixed energy and cannot fall into the nucleus.
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Energy Level
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Region around the nucleus where electrons are likely to be located.
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The only place electrons can exist
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Energy Levels
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The Sublevels of Energy levels
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s,p,d,f
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Ionic Bonding
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Occurs between a metal and a nonmetal, forming cations and anions. Involves the transferring of electrons.
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Covalent Bonding
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Occurs between two nonmetals. Involves the sharing of electrons.
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Hydrocarbons
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Compounds containing only carbon and hydrogen
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Alkanes
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Single bonded hydrocarbons Saturated
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Alkenes
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Double bonded hydrocarbons Unsaturated
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Alkynes
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Triple bonded hydrocarbons unsaturated
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Unsaturated hydrocarbon
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a hydrocarbon that does not have the maximum number of hydrogen atoms
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Saturated Hydrocarbon
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a hydrocarbon that has all spaces for hydrogen atoms filled
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Polymer
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A large covalently bonded molecule made of repeating units called monomers Nylon,PVC,Teflon,Kevlar
