Chemistry Final Exam Review

hypothesis

hypothesis

A testable prediction, often implied by a theory

independent variable

a variable that stands alone and isn't changed by the other variables you are trying to measure

control

In an experiment, the standard that is used for comparison

dependent variable

something that depends on other factors

quantitative measurement

a measurement that gives definite, usually numeric results

qualitative measurement

a measurement that gives descriptive, nonnumeric results

accurate

the closeness of a measured value to a standard or known value

precise

the closeness of two or more measurements to each other

sublimation

A change directly from the solid to the gaseous state without becoming liquid

condensation

The change of state from a gas to a liquid

freezing

The change of state from a liquid to a solid

melting

The change in state from a solid to a liquid

deposition

occurs when molecules settle out of a solution

law of conservation of mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

chemical property

a characteristic of a particular substance that can be observed in a chemical reaction. Some major chemical properties include flammability, toxicity, heat of combustion, pH value, rate of radioactive decay, and chemical stability.

physical property

A characteristic of a pure substance that can be observed without changing it into another substance

homogenous mixture

A mixture in which substances are evenly distributed throughout the mixture

heterogenous mixture

A mixture with uneven distribution of different substances, solids, liquids, gases.

atomic mass

the weighted average of the masses of the isotopes of an element

atomic number

the number of protons in the nucleus of an atom

isotope

A form of a chemical element in which the atoms have the same number of protons (part of the nucleus of an atom) but with a different number of neutrons (part of the nucleus of an atom)

valence electrons

The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.

ionic compound

compounds made up of ions that form charged particles when an atom (or group of atoms) gains or loses electrons

covalent compound

An element or chemical compound in which atoms are held together by covalent bonds

diatomic

any chemical compound that is made up of only two atoms.

single replacement reaction

a chemical change in which one element replaces a second element in a compound

double replacement reaction

a chemical reaction between two compounds where the positive ion of one compound is exchanged with the positive ion of another compound

synthesis reaction

a reaction in which two or more substances combine to form a new compound

decomposition reaction

a reaction in which a single compound breaks down to form two or more simpler substances

combustion reaction

a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light

precipitate

a solid that forms and settles out of a liquid mixture

saturated

A solution in which no more solute can be dissolved at a given temperature

supersaturated

a solution that holds more dissolved solute than is required to reach equilibrium at a given temperature

unsaturated

A solution that contains less than the maximum amount of dissolved solute in a concentration.

miscible

Two liquids that combine in any ratio to form a homogeneous solution

immiscible

incapable of mixing or attaining homogeneity

soluble

able to be dissolved

insoluble

incapable of being dissolved

calorie

Amount of energy needed to raise temperature 1 gram of water 1 degree C

joule

SI unit of energy

catalyst

substance that speeds up the rate of a chemical reaction

inhibitor

A substance that slows down or stops a chemical reaction

boyle's law

A principle that describes the relationship between the pressure and volume of a gas at constant temperature

charles' law

the law that states that for a fixed amount of gas at a constant pressure, the volume of the gas increases as the temperature of the gas increases and the volume of the gas decreases as the temperature of the gas decreases

endothermic

chemical reactions in which the reactants absorb heat energy from the surroundings to form products

exothermic

Chemical reactions that release energy

density

the mass of an object divided by its volume

mass

the amount of matter in an object

volume

The amount of space an object takes up

kinetic theory of matter

the idea that all matter is made up of tiny particles in constant motion

specific heat

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius

pauli's exclusion principle

no two electrons in an atom can have the same set of quantum numbers

hund's rule

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

rules of sig figs

1. non zero digits are significant

2. zeros appearing b/w nonzero digits = significant

3. zeros that appear in front of nonzero digits are NOT significant

4. zeros at the end and to the right ARE significant

5. zeros at the end of a no. may/may not be significant

how many sig figs in 246.32?

5

how many sig figs in 0.00340?

3

how many sig figs in 320001?

6

atomic number is...

number of protons + neutrons

in isotopic notation, what number is on top

mass number

in isotopic notation, what number is on bottom

atomic number

groups/families

Vertical columns on the periodic table

periods on periodic table

horizontal rows

s block is where on the PT?

far left (alkali and alkaline earth metals)

d block is where on the PT?

in the middle (trans. metals)

p block is where on the PT?

R hand side of PT (nonmetals)

where is f block on PT?

lower two rows (actinides and lanthanides)

trend of electronegativity

increases across a period, decreases down a group

trend of atomic radii

decreases as you move from left to right across a period and increases as you move down a group

which rules do NOT apply to noble gases

atomic radii

trend of ionization energy

increases across a period, decreases down a group

ionic bond

bond between a metal and a nonmetal

covalent bond

bond between two nonmetals

metallic bond

force that holds atoms together in a metallic substance

oxidation number

the total number of electrons that an atom either gains or loses in order to form a chemical bond

cation

(+) charged ion

anion

(-) charged ion

dipole-dipole force

exists between polar regions of diff. molecules

London dispersion forces

the intermolecular attraction resulting from the uneven distribution of electrons and the creation of temporary dipoles

ionization energy

amount of energy required to remove the atoms outermost e-.

VSEPR theory

states that repulsion between the sets of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible

endothermic rxn

absorbs heat energy

exothermic rxn

releases energy

Mendeleev organized the PT by...

inc. atomic mass

what kind of chemical bond is formed when electrons are transferred?

ionic bonding

ionic compounds have _____ melting points than covalent compounds

higher

ionic bonds form between ________ & __________

metals and nonmetals

during chemical bonding, non-metals tend to _________ e- to form ________

steal, equilibrium

when writing formulas for ionic compounds, the cation or anion is written first?

anion

name 4 ways to inc. the rate of rxn

add a catalyst, inc. temp., inc. surface area, saturate more

If the atoms that share electrons have an unequal attraction for the electrons, the bond is called

nonpolar

vol. and mass are ________ proportional to each other

directly

isotopes

atoms of the same element but with diff. no. of p+ and neutrons

the lowest and most stable energy state is known as the

ground state

Aufbau Principle

states that each electron occupies the lowest energy orbital available

Hund's Rule

orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, each with opposite spin direction

metals ______ e- to form a full octet whereas nonmetals _______ e- to form a full octect

lose, gain

precipitate

A solid that forms from a solution during a chemical reaction.

aqueous

dissolved in water

decomposition reaction

AB --> A + B