Chem Exam #2 (Ch 4-6)

diamagnetic

electrons are paired, pushed away from magnetic fields

paramagnetic

unpaired electrons, attracted to magnetic fields

atomic radius

distance between the nucleus of an atom + its valence shell

• increases ← and ↓

ionization energy

the min. energy required to remove an electron from a gaseous atom in the ground state

• increases —> and ↑

effective nuclear charge

actual magnitude of positive charge that is ‘experienced’ by an electron in the atom

electron affinity

the energy released when an atom in the gas phase accepts an electron

• increases —>

metals

shiny, malleable, good conductors

non-metals

dull, poor conductors

metalloids

moderate conductors

Alkali metals

group 1, +1 charge

Alkaline earth metals

group 2, +2 charge

Pnictogens

group 15, -3 charge

Chalcogens

group 16, -2 charge

Halogens

group 17, -1 charge

oxyanion

an anion that contains oxygen in the form A_xO_y^z-

How do the oxidation states go?

+1, +2, +3, +4, -3, -2, -1

Which elements have multiple charges?

2+/3+: Cr, Mn, Fe, Co, Ni,

2+: Zn, Cd, Sn, Pb

Cu: +/2+

Ag: +

Hg: 2+ 2/ 2+

covalent bonds ___ electrons

share

in polar covalent bonds electrons are ____ shared

unequally

in ionic bonds electrons are ____

transferred

ionic bonds usually have :

high melting points

the formation of ionic bonds releases a ___ amount of energy

large

cation

tends to lose all of its valence electrons, +

anion

tends to gain electrons, -

covalent bonds are ___ than ionic bonds, ___ conductors

weaker, poor

nonpolar/purely covalent (EN)

differ by < .5

polar covalent (EN)

differ by .5-2.0

ionic (EN)

differ by 2.0 or more

Dipole moment

quantitive measure of the polarity of the bond

polar characteristics

• hydrogen bonding

• asymmetric

nonpolar characteristics

• composed of 1 element

• noble gases

• only C+H

• symmetric

• sm EN diff

writing ionic compounds (binary)

name of cation (metal) + base name of anion (nonmetal) + -ide

writing ionic compounds (w/polyatomic)

name of cation (metal) + polyatomic ion

polyatomic naming rules:

per…ate: 1 more O

-ite: 1 less O

hypo…ite: 2 fewer O

what are the numbers for molecular naming

mono: 1

di: 2

tri: 3

tetra: 4

penta: 5

hexa: 6

hepta: 7

octa: 8

nona: 9

deca: 10

naming molecular compounds

prefix + 1st nonmetal + prefix + 2nd element base + -ide

naming hydrates

normal naming rules + prefix + hydrate

naming acids (binary)

hydro + nonmetal base + -ic + acid

naming acids (oxyanion)

-ate: oxyanion base name + -ic + acid

-ite: oxyanion base name + -ous + acid

finding core electrons:

total electrons - valence

formal charge

valence electrons - (dots) - (dashes)

• smallest diff = best lewis structure

Valence Shell Electron - Pair Repulsion Theory

approximate the geometry

1. e will arrange themselves to be as far apart

2. arrangements min. repulsive interactions

3. best results for sing bonds + main group elements

electron domains

lone pairs + electrons in bonds

2 e- domains =

linear

3 e- domains =

trigonal planar

4 e- domains =

tetrahedral

5 e- domains =

trigonal bipyramidal

6 e- domains =

octahedral

linear degree?

180

trigonal planar degree?

120

tetrahedral degree?

109.5

trigonal bipyramidal degree?

90 + 120

octahedral degree?

90

IMF’s ___ electrons while KE ____ molecules

pulls, seperate

intra vs inter molecular forces

intra: within molecule, keeps it together (strong)

inter: between molecules, det physical properties (weak)

IMF’s weakest to strongest

dispersion - dipole-dipole - H-bonding - ionic

Dispersion forces

heavier molecule=more electrons=stronger dispersion= higher M.P/B.P

larger SA=more dispersion= higher M.P./B.P.

dipole-dipole interactions

partially positive and partially negative

• polar molecules, opposites attract

H-bonding

H bonded to a sm highly EN atom (N, O, F)

• high boiling point and water solubility

Valence Bond Theory

1. a bond forms when single-occupied atomic orbitals on 2 atoms overlap (sigma/pi bonds)

2. 2 electrons shared in a region of orbital overlap must be of opposite spin

   1. formation of a bond results in a lower P.E. for the system

Hybrid Atomic Orbitals

the mixing of atomic orbitals to make ‘hybrid orbitals’

• turn element into excited state

• 2 orbitals to form 2 bonds

(usually move one electron from 2s—>2p)

sp =

linear

sp² =

trigonal planar

sp³ =

tetrahedral

sp³d =

trigonal bipyramidal

sp³d² =

octahedral

Steps for hybridization:

1. lewis structure

2. count e- domains

3. draw ground state orbital diagram

4. create a unpaired valence e- promotion = to the number of bonds in lewis structure

5. combine necessary atomic orbitals to generate hybrid

6. place e- in hybrid

Molecular Orbital Theory

traits of bonding and antibonding molecular orbitals

constructive combination

increase e- density (bonding orbital)

• covalent bonds

destructive combination

increase e- density (anti-bonding orbital)

bonding orbitals ____ the molecular are ____ in energy

stabilize, lower

anti-bonding orbitals ____ the molecular are ____ in energy

destabilize, higher

bond order

(bonding e-) - (anti-bonding e-) / 2

Which elements are for MO diagrams when no s+ p mixing?

O2, F2, Ne2

Which elements are for MO diagrams when s+ p mixing?

Li2, B2, C2, N2

ammonium

NH₄⁺

hydronium

H₃O⁺

peroxide

O₂^2-

hydroxide

OH^-

acetate

CH₃COO^-

cyanide

CN^-

azide

N₃^-

carbonate

CO₃^2-

bicarbonate

HCO₃^2-

nitrate

NO₃^-

nitrite

NO₂^-

sulfate

SO₄^2-

hydrogen sulfate

HSO₄^-

sulfite

SO₃^2-

hydrogen sulfite

HSO₃^-

phosphate

PO₄^3-

hydrogen phosphate

HPO₄^2-

dihydrogen phosphate

H₂PO₄^-

perchlorate

ClO₄^-

chlorate

ClO₃^-

chlorite

ClO₂^-

hypochlorite

ClO^-

chromate

CrO₄^2-

dichromate

Cr₂O₇^2-

permanganate

MnO₄^-