8.1 - 8.4

8.1 - 8.4 Bonding

Bond energy

• Energy required to break a bond
• Stronger bond = higher bond energy

Ionic bonding

• Transfer of electrons
• One atom loses e- (cation)
• One atom gains e- (anion)
• (+) attract (-) in ionic bond
• Between a metal and a nonmetal

Coulomb’s law

• Amount of energy between a pair of ions is coulombs law
• E= 2.31x10-19J*nm(Q1Q2/r)
• E has units of Joules
• Q1 and Q2 = numerical charges
• r = distance between ion centers
• When the value is negative it means that the ion pair has lower energy than the separate ions (attractive force)

Bond length

• The distance between the nuclei of the two atoms connected by a bond

Covalent bonding

• Electrons are shared by nuclei
• Non metals

Electonegativity

• The ability of an atom in a molecule to attract electrons to itself
• When 2 atoms share electrons unevenly (due to difference in electronegativity) a polar covalent bond forms
• Dipole moment: 

Bond polarity

• When bond polarity cancels out in a molecule (symmetry) there is no net dipole moment and the molecule is non-polar

Sizes of Ions

• Isolectric ions- same number of e-
•                                 P+              e-
• O2-                          8                10
• F-                            9                10
• Na+                         11               10
• Mg 2+                     12               10
• Al 3+                       13               10
• In isoelectric ions, as charge increases size decreases.