CHEM HL YEAR REVIEW

Element

The simplest form of matter that cannot be broken down.

Mixture

A combination of two or more substances that are NOT in a fixed ratio and retain individual properties.

Compound

A substance formed when two or more elements are chemically bonded in a fixed ratio.

Kinetic Molecular Theory

A theory that explains the physical properties of matter and changes of state.

Temperature (T)

The average kinetic energy of the particles in a substance.

Kelvin (K)

The SI unit of temperature that uses the same increments as Celsius.

Atomic Mass (A)

The mass of an atom, with the mass of the electron being negligible.

Atomic Number (Z)

The number of protons in the nucleus of an atom.

Isotopes

Atoms of the same element that have different numbers of neutrons.

Emission Spectra

The spectrum of light emitted by excited electrons returning to lower energy states.

Line Emission Spectrum

A spectrum that provides evidence for discrete energy levels of electrons.

Ionization Energy

The energy required to remove one mole of electrons from one mole of gaseous atoms.

Mole (mol)

An SI unit that quantifies the amount of a substance containing 6.02 x 10^23 entities.

Empirical Formula

The simplest whole number ratio of elements in a compound.

Ionic Bonding

Chemical bonding between a metal and a nonmetal resulting in charged ions arranged in a lattice.

Metallic Bonding

An attraction between a metal lattice and a sea of delocalized electrons.

Covalent Bonding

An electrostatic attraction between shared electron pairs and positive nuclei.

Electronegativity

The relative attraction an atom has for shared electrons in a bond.

VSEPR Shapes

Shapes of molecules based on electron pair repulsion, including linear, tetrahedral, etc.

Polymers

Large molecules made of repeating structural units called monomers.

Transition Elements

Elements that show variable oxidation states and have an incomplete d sublevel.

Lattice Enthalpy

The measure of the strength of the forces between the ions in an ionic solid.

Activation Energy

The energy required to initiate a chemical reaction.

Combustion

A chemical process in which a substance reacts with oxygen to produce heat and light.

Greenhouse Gases

Gases that absorb and emit infrared radiation, contributing to the greenhouse effect.

Hybridization

The mixing of atomic orbitals to form new hybrid orbitals for bonding.

Resonance Structures

Different possible configurations of a molecule that lead to the same molecular structure.

Mass Spectroscopy

An analytical method used to measure the mass-to-charge ratio of ions.

First Ionization Energy

The energy required to remove the outermost electron from a neutral atom.

Electron Affinity

The change in energy when an electron is added to a neutral atom.

Bond Enthalpy

The energy associated with breaking bonds in molecules.

Covalent Bond Enthalpy

The energy required to break a covalent bond in a gaseous molecule.

Atomic Radius

Half the distance between the nuclei of two atoms.

Condensation Polymers

Polymers formed by the elimination of small molecules, typically water.

Addition Polymers

Polymers formed by addition reactions without the loss of any small molecules.

Formal Charge

A calculation used to determine the most stable structure among possible Lewis structures.