ultimate chem review

updated regularly

molecules in nucleus

protons and neutrons

mass number

number of neutrons in nucleus

atomic number

number of protons in nucleus

isotopes

same number of protons and electrons but different number of neutrons

average atomic mass

based on the percentage of isotopes found in nature

valence electrons

electrons in the outermost shell (can be easily shared, gained or lost)

core electrons

electrons in the inner shell

atomic spectra

the electromagnetic emission from atoms and molecules

spectroscopy

a technique measuring electromagnetic emissions that is widely used in chemical analysis and in studies of the properties of atoms, molecules, ions, etc.

wave mechanical model

modern model of the atom, atoms have electrons in "orbitals" that are like clouds around the nucleus

quantum numbers

specify the properties of atomic orbitals and the properties of electrons in orbitals

pauli expulsion principle

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

hund’s rule

electrons do not pair up until they have to

aufbau principle

An electron occupies the lowest-energy orbital that can receive it

noble gas notation

shortcut→ find the closest noble gas (column 18) with fewer electrons than the element then finish configuration

transition elements

group 3-12

transition element properties

elements that have high melting points, often paramagnetic, tend to form salts when reacted w/ halogens ex; iron, copper, gold, silver, and titanium

electronegativity

a measure of the ability of an atom in a chemical compound to attract electrons

ionization energy

the amount of energy required to remove an electron from an atom

alpha decay

a nuclear reaction in which an atom emits a ________ particle consisting of two protons and two neutrons; this increases the atomic number by 2 and the mass number by 4.

beta decay

a nuclear reaction in which a neutron changes into a proton and into an electron, and the atoms emits a ______ particle, which is the electron; this increases the atomic number of the atom without changing the mass.

gamma radiation

electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength

covalent bond

a chemical bond that involves sharing a pair of electrons between atoms in a molecule

dipole-dipole attraction

attractive force resulting when polar molecules line up so that the positive and negative ends are close to each other

electrostatic repulsion

describes a force between particles with opposite electrical charges that causes them to push apart from one another

hybridization

several atomic orbitals mix to form the same total number of equivalent hybrid orbitals

hydrogen bond

a relatively weak bond formed between any hydrogen atom (which is covalently bound to a nitrogen or oxygen atom) and a nitrogen or oxygen with an unshared electron pair

ionic bond

formed when one or more electrons are transferred from one atom to another; metal and nonmetal

london dispersion forces

the intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles

metallic bond

a bond formed by the attraction between positively charged metal ions and the electrons around them

pi bond

when two p orbitals line up in parallel and electron clouds overlap. it exsits over a single bond.

resonance structure

a structure that occurs when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion

stable octet

the arrangement of eight electrons in the outermost shell of an atom

sigma bond

a bond formed when two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting the two atomic nuclei

van der waals forces

a slight attraction that develops between the oppositely charged regions of nearby molecules

VSERP

valance electron pair repulsion model / unshared electron pairs around the central atom

binary compound

ionic compounds when they are composed of only two different kinds of atoms

coefficient

a number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.

emperical formula

simplest whole \# ration of atoms in a compound

formula mass

the sum of the average atomic masses of all the atoms represented in the formula of any molecule, formula unit, or ion

molecular mass

the sum of the masses of all the atoms in a molecule

law of definite composition

chemical compounds are composed of a fixed ratio of elements as determined by mass.

law of multiple proportions

whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers

net ionic equation

includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution

percentage composition

the percentage by mass of each element in a compound

polyatomic ion

a covalently bonded group of atoms that has a positive or negative charge and acts as a unit

products

the elements or compounds produced by a chemical reaction.

reactants

a substance that takes part in and undergoes change during a reaction

stock system

a method for naming ions of elements that can form more than one possible positive charge by using a roman numeral after the ion name to denote the ion's charge

ternary compound

a compound that consists of three or more elements, usually containing

true formula

chemical formula that indicates the actual number of atoms of each element in one molecule of a substance

atmosphere

Layers of different gases that surround the Earth.

atmospheric pressure

the pressure exerted by atoms and molecules in the atmosphere surrounding Earth, resulting from collisions of these particles with objects

greenhouse effect

natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

manometer

a device used to measure the pressure of a sample of gas in a container.

boyle’s law

PV \= k

charles’s law

V/T \= k

combined gas law

P1V1/T1\=P2V2/T2 (constant n)

ideal gas law

PV \= n R T

dalton's law of partial pressures

total pressure of a gas is equal to the sum of the partial pressure of the component gases

graham's law

rate of diffusion of a gas is inversely proportional to the square root of its molecular weight

kinetic-molecular theory

a theory that explains that the behavior of physical systems depends on the combined actions of the molecules constituting the system

mercury barometer

an instrument that measures changes in air pressure, consisting of a glass tube partially filled with mercury, with its open end resting in a dish of mercury

ozone

a form of oxygen that has three oxygen atoms in each molecule instead of the usual two

pascal

the SI unit of pressure equal to one newton per square meter

standard pressure

1 atm or 101.3 kPa

standard temperature

One atmosphere and 273 K.

torr

the force per unit area exerted by the gas on its container, usually measured in atmospheres

acidic anhydride

a nonmetallic oxide that, when placed in water, reacts to form an acid solution

aeration

air is forced through the water to release unwanted gases, which reduces odor and improves taste

alloy

a mixture of two or more metals

boiling point

the temperature at which a liquid changes to a gas

brownian movement

kinetic energy spreads small suspended particles throughout the cytoplasm of the cell

colligative property

a property of a solution that depends on the number, not the identity, of the solute particles

concentrated

describes a solution that has a relatively large amount of dissolved solute

critical pressure

the lowest pressure at which the substance can exist as a liquid at the critical temperature

critical temperature

the temperature above which the substance cannot exist in the liquid state

crystal

an orderly, three-dimensional pattern of ions or atoms in a solid

deliquescent

compounds that remove sufficient water from the air to dissolve completely and form solutions

dilute

to lessen the concentration, force, or purity of by adding something

dynamic equilibrium

result of diffusion where there is continuous movement of particles but no overall change in concentration

endothermic

a chemical reaction that absorbs energy (heat)

efflorescent

hydrated crystals that lose the water of hydration on exposure to air at ordinary temperatures

exothermic

a chemical reaction that releases energy (heat)

heat of fusion

amount of energy required to change a substance from the solid phase to the liquid phase

heat of vaporization

the amount of energy required for the liquid at its boiling point to become a gas

"heavy" water

water containing an elevated concentration of molecules with deuterium

deuterium

an isotope of hydrogen with one proton and one neutron in the nucleus having an atomic weight of 2.014

hydrate

a compound that has a specific number of water molecules bound to its atoms

le chatelier's principle

states that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress

melting point

the temperature at which a solid becomes a liquid

miscible

describes two liquids that are soluble in each other

immiscible

liquid solutes and solvents that are not soluble in each other

molality

the concentration of a solution expressed in moles of solute per kilogram of solvent

molarity

a common measure of solute concentration, referring to the number of moles of solute per liter of solution

mole fraction

the ratio of the moles of solute in solution to the total number of moles of both solvent and solute

normality

gram equivalent weight of solute per liter of solution, often denoted by N

phase equilibrium

when the rates of evaporation and condensation equalize

polarity

a lack of electrical symmetry in a molecule; charge differences on opposite ends of a structure

saturated

unable to dissolve any more solute