Chemical Compounds and Bonding Ionic compounds ionic bond steal (transfer) electrons Molecules covalent bond share electrons

Properties of Ionic Compounds Metal/nonmetal Ionic bonds Transfer electrons Strong +/- attraction High boiling/melting point Solids Brittle Molten Conduct heat/electricity

Molecules 2 non-metals Covalent bonding – sharing electrons Weak attractions Low boiling/melting points Gases,solids, liquids, Do not conduct electricity

Electron Dot Formulas for elements Show valence electrons only ***Remember families

Octet Rule An atom will gain or lose electron to have an octet (or filled) valence energy level

Ionic bonds Electron dot write cation, anion

Covalent bonding Share electrons to form an octet ****except H – it shares to get 2 Single double triple coordinate bonds Electron- dot formula Structural formula

Structural Formula Shows bonding without electrons 1 pair of electrons equals 1 single bond

Make a table Chemical Electron dot Structural Bond Molecule Formula FormulaFormula Type Type

Electronegativity Desire to steal another atom’s electron EN differenceType of bond 0-.4nonpolar covalent.5-1.9polar covalent 2.0 +ionic bond

Determine bond type Use Electronegativity table p440 H=2.1 Cl=3.0Br=2.8 F=4.0O=3.5I=2.1 C=2.5 H=2.1 Na=.9F=4.0 S=3.0N=3.0 P=2.5K=0.8 Si-2.0Mg=1.0

Molecule Type Look at the molecule polar – 2 different “ends” non-polar – same “ends”

Cl 2 S 2 P 2 H 2 O CF 4 *****remember C CF 3 H

C 2 H 6 H 2 O 2 HCN C 2 H 4 CH 2 O SiO 3 -2 PO 4 -3

Molecular shapes see page 457 Linear Trigonal planar Tetrahedral Trigonal pyrimidal Bent

Exceptions to Octet rule BF 3 PCl 5

Resonance Having 2 or more correct electron dot structures that are different CO 3 -2

VSEPR Theory valence shell electron pair repulsion theory Bond angles are different ( usually less) due to electrons repelling other electrons Water should be o but it is o