1. Structure and Bonding

Question 1

Atomic structure

Answer 1

• positively charged nucleus (very dense, protons and neutrons) and small
• negatively charged electrons
• diameter = 2 x 10^-10 m (200 pm)

Question 2

Atomic Number (Z)

Answer 2

number of protons in the atom’s nucleus

Question 3

Mass Number (A)

Answer 3

the number of protons plus
neutrons

Question 4

Isotopes

Answer 4

atoms of the same element that have
different numbers of neutrons and therefore different
mass numbers

Question 5

Atomic Mass

Answer 5

the weighted average mass in atomic mass units (amu) of an element’s naturally occurring isotopes

Question 6

Quantum Mechanics

Answer 6

describes electron energies
and locations by a wave equation

• wave function (orbital) solution of wave equation

Question 7

Shapes of Atomic Orbitals for
Electrons

Answer 7

s, p, d, and f

Question 8

s orbitals

Answer 8

spherical, nucleus at center

Question 9

p orbitals

Answer 9

dumbbell-shaped, nucleus at middle

Question 10

d orbitals

Answer 10

elongated dumbbell-shaped, nucleus at
center

Question 11

Orbitals are grouped in shells of increasing size and
energy

Answer 11

1st shell = 2 electrons
2nd shell = 8 electrons
3rd shell = 18 electrons

Question 12

p-Orbitals

Answer 12

Lobes of a p orbital are separated by region of
zero electron density, a node

Question 13

Ground-state electron configuration (lowest
energy arrangement)

Question 14

Lewis structures (electron dot)

Answer 14

show valence
electrons of an atom as dots

Question 15

Kekule structures (line-bond structures)

Answer 15

have a line
drawn between two atoms indicating a 2 electron
covalent bond.

Question 16

nonbonding electrons, or lone-pair electrons

Answer 16

Valence electrons not used in bonding

Question 17

Valence Bond Theory

Answer 17

Electrons are paired in the overlapping orbitals and are attracted to nuclei of both
atoms

Question 18

Bond Energy

Answer 18

e.g. 436 kJ/mol is released when bond forms; absorbed when bond breaks

Question 19

Bond Length

Answer 19

• Distance between
  nuclei that leads to
  maximum stability
• If too close, they
  repel because both
  are positively
  charged
• If too far apart,
  bonding is weak

Question 20

Molecular Orbital (MO)

Answer 20

where electrons are most likely
to be found (specific energy and general shape) in a
molecule

bonds result from combination
of atomic orbitals to give molecular orbitals, which belong to the
entire molecule

Question 21

Additive combination (bonding) MO is lower in energy

Subtractive combination (antibonding) MO is higher
energy

Question 22

Electrons occupy orbitals around the nucleus.

Question 23

Sigma (s) bonds

Answer 23

Circular cross-section and are formed by
head-on interaction

Question 24

Pi bonds

Answer 24

“dumbbell” shape from sideways interaction of p
orbitals

Question 25

Atoms such as nitrogen and oxygen hybridize to form strong,
oriented bonds. The nitrogen atom in ammonia and the oxygen atom in
water are sp3
-hybridized

Question 26

1-methylethyl

Answer 26

Isopropyl

Question 27

1-methylpropyl

Answer 27

Secbutyl

Question 28

2-methylpropyl

Answer 28

Isobutyl

Question 29

1,1-dimethylethyl

Answer 29

Tertbutyl

Question 30

3-methylbutyl

Answer 30

Isopentyl/Isoamyl

Question 31

2,2-dimethylpropyl

Answer 31

Neopentyl