Chemistry 1A Midterm II Review

mono

1

di

2

tri

3

tetra

4

penta

5

hexa

6

hepta

7

octa

8

nona

9

deca

10

chemical compounds

combo of elements through chemical bonding

3, ionic, covalent, metallic

_types of chemical bonding:___

chemical formulas

way of specifying ratios

octet rule

elements tend to want to achieve shells with 8 electrons

ionic / covalent bonding (exchange / share electrons)

octet rule can be achieved by

ionic bonding

metal cation give electron to nonmetal anion

cations border anions and vice versa

crystal lattice description

formula unit

simplest whole number ratio of cations to anions

hard and brittle, tightly held electrons = not conductive as solid but are in water, high melting and boiling points

ionic solid properties

covalent bonding

2 nonmetals share electrons

lewis dot structure

illustrates bonding electron pairs and lone pairs in covalent compounds/molecules

molecular formula

# of each type of atom in 1 molecule; does not reduce to lowest ratio

electrostatic interactions

distance between atoms in a covalent bond is a matter of balancing ______

electron to nucleus

attraction between these two pulls two nonmetal atoms together

bond length

optimum distance with lowest potential energy 

bond energy 

stability gained from bond formation; strength of bond; energy required to break bond

low melting / boiling points, not conductive

properties of covalent compounds

polar covalent bonds

when 2 atoms share electrons unequally

dipole moment

separation of charge, measured in Debye (D)

nonpolar covalent bond

EN < 0.4

polar covalent bond

EN < 1.7

ionic bond

EN > 1.7

array of nuclei held together by sea of delocalized electrons (electron sea model)

metallic bonding description

alloy

mix of metals

variable composition

metal alloys do not need ratios or charge balance because ____

yes, metal should still be primary

can nonmetals or metalloids be in metal alloys?

malleable, good conductors, moderate melting points, high boiling points

metallic solid properties

lewis structure

describes connections between atoms formed by valence electrons in a molecule

electron deficient

having less than 8 valence electrons

free radical

species with odd number of electrons (leaves one lone electron)

expanded octet

Period 3+, can accomodate more than 8 electrons

formal charge

chrage of an atom in a molecule / polyatomic ions assuming even distribution of electron in a bond

resonance hybrid

a molecule that may imply formal charges and bond orders have non-integer values

arrow pushing / curved arrow formalism

shows relationship between resonance forms

VSEPR Theory

in molecules, electron groups repel each other

steric number

number of bonded atoms + lone pairs around central atom

linear, 180

SN=2

Trigonal Planar

SN = 3

trigonal planar, 120

molecular shape for…..electron group: trigonal planar, 0 lone pairs

bent, <120

molecular shape for…..electron group: trigonal planar, 1 lone pair

tetrahedral

SN=4

tetrahedral, 109.5

molecular shape for…..electron group: tetrahedral, 0 lone pairs

trigonal pyramidal, <109.5

molecular shape for…..electron group: tetrahedral, 1 lone pair

bent, <109.5

molecular shape for…..electron group: tetrahedral, 2 lone pairs

trigonal bipyramidal

SN=5

trigonal bipyramidal, 120 equatorial, 90 axial

molecular shape for…..electron group: trigonal bipyramidal, 0 lone pairs

seesaw, <120 equatorial, <90 axial

molecular shape for…..electron group: trigonal bipyramidal, 1 lone pair

t-shaped, 90

molecular shape for…..electron group: trigonal bipyramidal, 2 lone pairs

linear, 180

molecular shape for…..electron group: trigonal bipyramidal, 3 lone pairs

octahedral

SN=6

octahedral, 90

molecular shape for…..electron group: octahedral, 0 lone pairs

square pyramidal, <90

molecular shape for…..electron group: octahedral, 1 lone pair

square planar, 90

molecular shape for…..electron group: octahedral, 2 lone pairs

full octet if you can, minimize total formal charge, for charged ions negative charges on more electronegative atoms and positive charges on less electronegative atoms

resonance rules for most important resonance contributor

sp

2 things

sp^2

3 things

sp^3

4 things

sp^3d

5 things

sp^3d^2

6 things

Valence Bond Theory

Bonds are formed by the overlap of orbitals of adjacent atoms.

localized orbitals

valence bond theory only focuses on electrons in

Hybridization

atomic orbitals mixing to form same number of hybridized orbitals

sigma bond

from end to end overlap or s-orbital overlap

pi bond

from the side to side overlap of p or sp and sp² hybridized orbitals

only requires end to end overlap to maintain bond

why is there free rotation about single bonds

requires side to side overlap, high energy barrier

why is there no free rotation about double and triple bonds

Molecular Orbital Theory

Introduces idea of molecular orbitals and delocalized orbitals; electron behavior in molecules

Molecular Orbitals

Formed from combo of orbitals from multiple atoms in a molecule

bonding mo

When atomic orbitals overlap constructively or in phase, they form ____

antibonding mo

When atomic orbitals overlap destructively or out of phase, they form ___

Heteronuclear diatomics

diatomic molecules with different atoms

homonuclear diatomics

diatomic molecules with same atoms

higher

less electronegative = ____ on the mo energy diagram

1

sigma 2p has ___ orbitals