Chemical Formulas and Nomenclature

Chemical Formulas

represent the number of atoms of each element in a compound

Atom

the base unit of any element, smallest piece of an element that still has the qualities of the element

ions

charged atoms [see my note “isotopes and ions” for more details]

cation

positively charged atoms/ions (typically metals)

anion

negatively charged atoms/ions (typically metals)

polyatomic ions

groups of covalently bonded atoms that have a charge

Ionic Compound

contain a cation (metal) and an anion (nonmetal)

molecule

two or more atoms (usually nonmetals) that are covalently bonded

diatomic molecule

elements that in their natural form are only found in molecules of two atoms

Binary Compound

Compound of only two elements

Binary Type I: Ionic Compound

Containing one cation and one anion both with known charges (no transition metals except Al, Zn and Ag)

Binary Type II: Ionic Compound

Containing one cation and one anion with the cation being any transition metal except Al, Zn, and Ag

Binary Type III: Covalent Molecular Compound

Containing two nonmetals, doesn’t have a charge

Ternary Compounds:

compound containing 3 or more elements

1

Mono

2

Di

3

Tri

4

Tetra

5

Penta

6

Hexa

7

Hepta

8

Octa

9

Nona

10

Deca