COVALENT COMPOUNDS Unit 2 COVALENT BOND

Forms between two non-metals! Electrons are shared!  Co= share  Valent = electrons Since electrons are shared, no need to balance charges Covalent bonds form molecules.

Molecule - group of neutral atoms held together with a covalent bond

Diatomic molecules – molecule consisting of 2 atoms  MOLECULES H2O2Br2F2I2N2Cl2

Compound composed of molecules is a molecular compound. MOLECULAR COMPOUNDS

Molecular Compounds Properties  Gases or liquids  Low melting/boiling points  Usually made from 2 nonmetals bonded covalently  Do not conduct electricity (solid or dissolved) Molecular chemical formula shows how many atoms of each element a molecule contains.

 H2O – Molecular formula of water  2 Hydrogen atoms, 1 Oxygen atom

 CO2 – Molecular formula for Carbon Dioxide MOLECULAR  1 Carbon atom, 2 Oxygen atoms FORMULAS H:H - Lewis Dot H-H – Structural Formula

H2 – Molecular chemical formula LEWIS STRUCTURES COVALENT BONDING

 To draw a Lewis Structure, one must know the types of atoms in the molecule, the number of atoms in the molecule and the number of valence electrons for each atom in the molecule. DOUBLE & TRIPLE COVALENT BONDS

Sharing a pair of electrons creates a single covalent bond

Sharing more than one pair of electrons creates double and triple covalent bonds.  2 shared pairs – Double covalent bond  3 shared pairs – Triple covalent bond  Carbon, Nitrogen, Oxygen 1. First element is named first, using the full name of the element

2. The second element is named by dropping ending and adding RULES FOR “–ide” NAMING 3. Prefixes are used to denote # COVALENT of each atom present COMPOUNDS 4. Prefix mono- is never used on the first element

5. Do not reduce the subscripts PREFIXES EXAMPLE

BF3  boron trifluoride

N2O3  dinitrogen trioxide

CO2  carbon dioxide CO  Carbon monoxide NO H O NAMING 2 PRACTICE N2O5 PROBLEMS CO

CCl3 Nitrogen monoxide

Dihydrogen monoxide

ANSWERS Dinitrogen pentoxide Carbon monoxide

Carbon trichloride WRITING PRACTICE PROBLEMS

Carbon Nonafluoride

Diphosphorous monoxide

Tetraoxygen tetrasulfide