Covalent Bonding Concept Polarity VSEPR Theory

Single Covalent Bonds Formed when a pair of electrons is shared between two atoms. – Example: H 2 A dash is used to show a shared pair of electrons: H – H Structural formula – chemical formulas that show the arrangement of atoms in molecules and polyatomic ions. Unshared pairs – pairs of valence electrons that are not shared between atoms.

Common Diatomic Elements NameChemical FormulaStructure FluorineF2F - F ChlorineCl2Cl – Cl BromineBr2Br – Br IodineI2I-I HydrogenH2H-H NitrogenN2N≡N OxygenO2O-O

Double and Triple Bonds Double bonds – involve 2 shared pairs of electrons. (ex) O = C = O Triple bonds – involve 3 shared pairs of electrons. (ex) C ≡ O Covalent compounds: water, ammonia, methane, and carbon dioxide. Water Ammonia Methane Carbon dioxide

Coordinate Covalent Bonds When one atom contributes both bonding electrons in a covalent bond. – Example: carbon monoxide C ≡ O -The oxygen atom contributes the third pair of electrons in the triple bond in order for the atoms to both meet the octet rule (another way to reach stability)

VSEPR Theory Valence Shell Electron Pair Repulsion – Basically means that shared pairs of electrons want to be as far from each other as possible. Resulting shapes: – Linear – Trigonal planar – Bent triatomic – Pyramidal – Tetrahedral – Trigonal bipyramidal

Polarity Bonded electrons are shared unequally. – Determined by electronegativity differences. Electronegativity differenceType of Bond 0.0 – 0.4Covalent (nonpolar) 0.4 – 1.0Covalent (moderately polar) 1.0 – 2.0Covalent (very polar) ≥ 2.0Ionic

Examples Water example Pg. 429 #53 (do not do letter f)