Molecular Geometry Chem Test

linear, 180

2 bonded atom, 0 lone pairs

trigonal planar, 120

3 bonded atoms, 0 lone pairs

bent, 120

2 bonded atoms, 1 lone pair

tetrahedral, 109.5

4 bonded atoms, 0 lone pairs

trigonal pyramidal, 109.5

3 bonded atoms, 1 lone pair

bent, 109.5

2 bonded atoms, 2 lone pairs

trigonal bipyramidal, 120 & 90

5 bonded atoms, 0 lone pairs

octahedral, 90

6 bonded atoms, 0 lone pairs

Chemical bond vs. metallic bond

A chemical bond is an attraction between atoms that allows the formation of chemical substances, while a metallic bond is a type of bonding that occurs in metals where electrons are shared among a lattice of metal atoms.

And ionic bond forms what kind of atoms?

Anions (-) and cations(+)

How are electrons used in a covalent bond?

They are shared between atoms; can be polar where they are unevenly distributed, or nonpolar where the sharing is equal.

When are metallic bonds formed?

Between metals

What are the properties of metallic bonds?

Same as a metal’s: malleable, ductile, good conductors

How is the strength of a metallic bond determined?

By heat of vaporization

How do you determine whether a bond is polar, nonpolar, or ionic?

By subtracting their electronegativities: less than .4 is nonpolar, between .4 and 1.7 is polar covalent, and greater than 1.7 is ionic

What kinds of elements do ionic bonds form between?

Metals and nonmetals

Properties of ionic bonds:

Strong electrostatic force, high melting and boiling points, good conductors in solution

Properties of covalent bonds:

Weak forces, low melting and boiling points, poor conductors in solution

Exceptions to the octet rule:

H: 2, Be: 4, B: 6, P: 10, S:12

What are resonance structures?

Molecules not represented by a single Lewis structure

How do you determine formal charge?

1. Start with # of valence electrons

2. Subtract number of bonds

3. Subtract number of unshared electrons

What can the molecular geometry of a molecule affect?

Shape and reactivity, melting and boiling points, biological activity, flavor and aroma

Nonpolar or polar molecule?

All nonpolar bonds = nonpolar molecule

Molecules with at least one polar bond will be polar

EXCEPT if the molecule is symmetrical and there are no lone pairs on the central atom, then it is polar

LDF

Forces for nonpolar, weak

DD

For all polar molecules that aren’t hydrogen bonded, strong

Hydrogen bonds

Strongest, between hydrogen and N O or F, polar