Element

a substance that cannot be broken down to other substances by chemical reactions.

a substance consisting of two or more different elements combined in a fixed ratio.

Elements required by an organism in only minute quantities.

Ex: Iron

The smallest unit of matter that still retains the properties of an element

electrically neutral subatomic particles

electrically negative subatomic particles

Protons

Electrically positive subatomic particles

consists of protons and neutrons; at center of atom

a unit of measurement for atoms and subatomic particles; named after John Dalton who developed atomic theory.

1 Dalton = 1 amu (atomic mass unit)

Protons/neutrons have mass of 1 amu

the number of protons in the nucleus (and consequently the number of electrons in the atom unless otherwise specified)

sum of protons and neutrons in the nucleus of an atom

the total mass of an atom - equal to the mass number

An atom that has more neutrons than other atoms of the same element (and therefore a greater mass)

These atoms still have the same number of protons though.

an isotope in which the nucleus decays spontaneously, giving off particles and energy.

used in bio to date fossils, follow atoms through metabolism 

EX: Carbon-14

the capacity to cause change

The energy that matter possesses because of its location or structure.

The more distant an electron is from the nucleus, the greater its potential energy. An electron's potential energy is determined by its energy level (NOTE: electrons can't exist b/w energy levels)

EX: water in a reservoir on a hill has potential energy because of its altitude.  When gates of reservoir are opened, the water  runs downhill and the energy can be used to do work.

electrons in the outermost shell (valence shell) that mostly contribute to the chemical behavior of an atom.

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms.  The bonded atoms gain complete outer electron shells (an octet)

two or more atoms held together by covalent bonds

Molecular Formula

indicates what atoms the molecule consists of.

EX: H2

Represents both the atoms and bonds that the molecule consists of.

EX: H-H

The attraction of a particular kind of atom for the electrons of a covalent bond; the more electronegative an atom, the more it pulls shared electrons toward itself.

charged atom (or molecule)

cation = positive

anion = negative

when cations and anions attract each other;

formed by ionic compounds, or salts (bonds are lattice like)

Hydrogen Bond

forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom

Weak attractions between molecules or parts of molecules that result from localized charge fluctuations.

The making and breaking of chemical bonds, leading to changes in the composition of matter

EX: 2H2 + O2 --> H2O

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time.