Chemistry Terms

Atom

Smallest particle, zero charge

chemical reaction

process that changes one set of chemicals into another set of chemicals

periodic table

A chart of the elements showing the repeating pattern of their properties, arranged by atomic number

atomic number

the number of protons in an atom (Z)

atomic mass

Number of protons and neutrons (A)

Compound

a thing that is composed of two or more separate elements, different properties than the original elements

Groups

columns on the periodic table (18)

Periods

Horizontal rows on the periodic table (7)

Main Group 1

alkali metals, 1 valence electron

Main group 2

alkaline earth metals, 2 valence electrons

main group 7

Halogens, 7 valence electrons

main group 8

noble gases, 8 valence electrons

Elements 58-71

Lanthanides

Elements 90-103

Actinides

Elements 93+

Transuranium metals

subatomic particles

protons, neutrons, electrons

Amu

atomic mass unit

Neutron

A small particle in the nucleus of the atom, with no electrical charge (0 charge, 1 amu)

Electron

A subatomic particle that has a negative charge (-1 charge, 1/1840 amu)

Proton

positively charged particle (+1 charge, 1 amu)

Electronic arrangement

The position and order of electrons in the different energy levels (number of electrons in each energy level: 2n to the power of 2)

Valency

the number of bonds an atom can form

covalent bond

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

Allotropes

Different forms of the same element

allotropes of carbon

diamond, graphite, fullerene

octet rule

atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas, usually eight valence electrons

Isotopes

Atoms of the same element that have different numbers of neutrons

metallic bond

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

intermolecular forces

forces of attraction between molecules

intramolecular forces

forces within molecules

Alloys

mixtures of two or more metals

rate

A ratio that compares two quantities measured in different units

collision theory

atoms, ions, and molecules can react to form products when they collide, provided that the particles have enough kinetic energy and with the correct orientation

reaction pathway

A series of steps tracing the reaction of a reactant to form a product it cannot form directly.

ionic bonding

Transfer of electrons from metal atom to non-metal atom to form the octet configuration.

metallic bond

attraction between positive metal ions and negative free/delocalized electrons