 Formed between two non-metals  Valence electrons are shared between atoms

 Contain just two different types of non-metal elements

 Covalent compound have a few rules to naming to those of ionic compound  When non-metals combine they can form several different covalent compounds Example: Carbon and oxygen combine to form two common covalent compounds CO 2 and CO Each of these compounds have their own names

1. Always write/name the element with more metallic character first. Metallic character increases going from right to left, and top to bottom on the Periodic Table.

2. Then write/name the second (less metallic) element, changing the ending of its name to –”ide”

3. Since nonmetals often combine in different proportions to form a number of different compounds, prefixes must be included in the names to indicate the numbers of each kind of atom present.

Number Prefix 1 mono- 6 hexa- 2 di- 7 hepta- 3 tri- 8 octa- 4 tetra- 9 nona- 5 penta- 10 deca-

P4S3 Tetraphosphorus trisulfide

 The mono- prefix is usually not used for the first element in the formula.  Example: BCl 3 boron trichloride

 Never use any prefixes at all for simple covalent compounds containing Hydrogen  Example: HF hydrogen fluoride

 The "o" and "a" endings of these prefixes are dropped when they are attached to "oxide."  Example: N 2 O 5 dinitrogen pentoxide

 Generally, they are in the same left-to-right order that they have on the periodic table, except that you would have to squeeze hydrogen in between nitrogen and oxygen.  Examples: NH3 ammonia CH4 methane H2O water

 Element that consists of two atoms combined Examples: F 2 fluorine N 2 nitrogen

SiF 4 silicon tetrafluoride

N2S3N2S3 dinitrogen trisulfide

HBr hydrogen bromide

Br 2 bromine

N 10 O 4 decanitrogen tetroxide

B2H6B2H6 diboron hexahydride

NBr 3 nitrogen tribromide

SCl 6 Sulfur hexachloride

P2O5P2O5 diphosphorus pentoxide

N3SN3S trinitrogen monosulfide

P8O7P8O7 octaphosphorus heptoxide

SbBr 3 Antimony tribromide

B 6 Si Hexaboron silicide

ClO 2 Chlorine dioxide

HI Hydrogen iodide

IF 5 Iodine pentafluoride

N2O3N2O3 Dinitrogen trioxide

NH 3 ammonia

PI 3 Phosphorus triiodide

P4S5P4S5 Tetraphosphorus pentasulfide

O2O2 oxygen

SeF 6 Selenium hexafluoride

Si 2 Br 6 Disilicon hexabromide

SCl 4 Sulfur tetrachloride

CH 4 methane

B 2 Si Diboron silicide

NF 3 Nitrogen trifluoride