Covalent Bonds

Atoms can become stable by sharing electrons. Shared e - are part of the outer energy level of both atoms. occurs between elements close to each other on the periodic table (primarily non-metals) NO CHARGES because NO IONS!!

molecule – result of 2 or more covalently-bonded atoms diatomic molecules – 2 atoms of same element bonded together in effort to be more stable occur in nature bonded together instead of as single atom H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 BrINClHOF

methane CH 4

Sigma bonds – single covalent bonds occur when one electron pair shared in area between 2 atoms outer orbitals of each atom overlap or merge Some atoms become stable by forming more than one covalent bond. Double – two shared pairs Triple – three shared pairs Strength of covalent bond depends on the distance between nuclei (bond length) More bonds, smaller distance, shorter bond length = stronger bond Single bonds are weaker than double bonds that are weaker than triple bonds.

Draw electron dot diagrams for the following: 1. PH 3 2. CCl 4 3. CO 2

Naming Covalent molecules 1. First name stays the same except if subscript is 2 or more 2. Second name ending is –ide. 3. Always use a prefix with second element. EX: CO N2O5N2O5

writing formulas 1. DO NOT look for charges! 2. Use prefixes to find subscripts. 3. Subscripts are not always in lowest whole number ratio. EX: dinitrogen tetrafluoride carbon tetrachloride