chem 115 exam 3

Ionic Bonding

• metal and nonmetal

• electrons are transferred

• Lattice energy

• hard, rigid, brittle, high melting points

• doesn’t conduct electricity when its solid because ions don’t move

Covalent Bonding

• nonmetal and nonmetal

• electrons are shared

Metallic Bonding

• metal and metal

• electrons are delocalized

Bond Length

• distance between nuclei of bonded atoms

• increases when atomic sizes are larger

• increases when bond order (number of bonds) decreases

Bond Strength

• increases when atomic size is smaller

• increased when bond order (number of bonds are higher)

Bond Energy

• energy needed to break attractions between nuclei and shared electrons

Relationship between bond length and bond strength

Inverse, because of Coulumb’s Law

How to find larger lattice energy

1. check charges: multiply absolute values

   1. greater charge = bigger lattice energy

2. Check ionic radii: add radii or check periodic table and use trend

   1. greater radii = less lattice energy b/c inverse

Bond Polarity

• how unequal bonds are

Nonpolar Covalent Bond

• basically the same because the electronegativities are very close, so electrons are shared equally

Polar Covalent Bond

• electrons are shared unequally

Ionic Bond

• electronegativities are so far apart that electrons are completely transferred from one atom to another

Heat of Sublimation

solid → gas

ex: K(s) → K(s)

Ionization Energy

Lose electrons

ex: K → K⁺ + e^-

Electron Affinity

Gain Electrons

ex: Br + e^- → Br^-

Bond Energy

Split to single atoms

ex: 2Br₂ → 2Br

Heat of Formation

Makes 1 solid mole

ex: K(s) + ½ Br(g) → Br(s)

Linear

• 2 bonds

• 180 degrees

Trigonal Planar

• 3 bonds, 0 lone pairs

• 120 degrees

Bent (3)

• 2 bonds, 1 lone pair

• 117.5 degrees

Tetrahedral

• 4 bonds

• 109.5 degrees

Trigonal Pyramidal

• 3 bonds, 1 lone pair

• 107 degrees

Bent (4)

• 2 bonds, 2 lone pairs

• 104.5 degrees

Trigonal Bipyramidal

• 5 bonds

• 90 and 120 degrees

Octahedral

• 6 bonds

• 90 degrees