Bonding and Chemical Interactions

Question 1

chemical bonds

Answer 1

formed via the interactions of valence electrons

Question 2

octet rule

Answer 2

atom tends to bond with other atoms such that it has eight electrons in its outermost shell

Question 3

Incomplete octet

Answer 3

elements that are stable with fewer than 8 electrons in valence shell:

• hydrogen (2)
• helium (2)
• lithium (2)
• beryllium (4)
• boron (6)

Question 4

expanded octet

Answer 4

element that can hold greater than eight electrons

• period three elements
• phosphorus (10)
• sulfur (12)
• chlorine (14)
• …

Question 5

odd numbers of electrons

Answer 5

any molecule with an odd number of valence electrons cannot distribute those electrons to give eight to each atom

Question 6

elements that always follow octet rule

Answer 6

carbon, nitrogen, oxygen, fluorine, sodium and magnesium

Question 7

ionic bonding

Answer 7

one or more electrons from an atom with a low ionization energy (metal) are transferred to an atom with a high electron affinity (nonmetal)

Question 8

covalent bonding

Answer 8

electron pair is shared between two atoms, typically two nonmetals

Question 9

coordinate covalent

Answer 9

when both of the shared electrons are contributed by one one of the two atoms

Question 10

cation

Answer 10

atom that loses an electron

Question 11

anion

Answer 11

atom that gains an electron

Question 12

ionic compound characteristics

Answer 12

• very high melting and boiling points
• dissolve readily in water/polar solvents
• good conductors of electricity
• form a crystalline lattice, consisting of repair positive and negative ions

Question 13

covalent compound characteristics

Answer 13

• relative weak IMFs
• lower melting and boiling points
• poor conductors of electricity
• do not break down into constituent ions

Question 14

bond order

Answer 14

number of shared electron pairs between two atoms

Question 15

bond length

Answer 15

average distance between the two nuclei of atoms in a bond; more bonds equals shorter bond length

Question 16

bond energy

Answer 16

energy required to break a bond by separating its components into their isolated, gaseous states; more bonds = more energy required, stronger bond

Question 17

polarity

Answer 17

occurs when two atoms have a relative difference in electronegativities

Question 18

non polar covalent bond

Answer 18

no separation of charge; H2, N2, O2, F2, CL2, BR2, I2; any atom with E- difference less than .5

Question 19

polar covalent bond

Answer 19

one atom is slightly -, one is slightly +; E- differences between .5 and 1.8

Question 20

dipole moment

Answer 20

p=qd
p= dipole moment
q=magnitude of the charge
d=displacement vector separating the two partial charges
measured in Debye units (coulomb-meters)

Question 21

Lewis dot diagram

Answer 21

chemical symbol of an element surrounded by dots, each representing one of the valence electrons

Question 22

Lewis structure rules

Answer 22

1. draw backbone of compound (H-C-N)
2. draw single bonds between each (2 dots)
3. Complete the octets of all atoms bonded to the central atom, using the remaining dots
4. Place any extra on central atom
5. if central atom has less than the octet, draw in multiple bonds

Question 23

formal charge

Answer 23

V-N(nonbonding)-0.5N(bonding)

V=normal number of e- found in shell

Question 24

resonance

Answer 24

two or more lewis structures that demonstrate the same arrangement of atoms but differ in placement of electrons

Question 25

resonance hybrid

Answer 25

actual structure of the compound is a hybrid of its resonance structures

Question 26

Lewis structure stability

Answer 26

- small or no formal charge is most stable - less separation between opposite charges is preferred - negative charges on more electronegative atoms is more stable

Question 27

Steps to use Valence Shell Electron Pair Repulsion (VSEPR) Theory

Answer 27

- Draw lewis dot structure - Count total number of bonding and nonbonding e- pairs on the central atom - arrange electron pairs around central atom so they are as far apart as possible

Question 28

VSEPR theory geometries

Answer 28

- (2)Linear:180 degrees - (3)Trigonal planar: 120 degrees - (4)Tetrahedral:109.5 degrees - (5)Trigonal bipyramidal: 90, 120, 180 degrees - (6)Octahedral: 90, 180 degrees

Question 29

electronic geometry v molecular geometry

Answer 29

- electronic geometry describes the spatial arrangement of all pairs of electrons around the central atom, including both bonding and lone pairs - molecular geometry describes only the spatial arrangement of bonding electrons

Question 30

coordination number

Answer 30

number of atoms that surround and are bonded to the central atom

Question 31

molecular orbital

Answer 31

describes the probability of finding the bonding electrons in a given space

Question 32

London dispersion force

Answer 32

attractive/repulsive forces of rapidly shifting dipoles between molecules; weakest of all IMFs

Question 33

dipole-dipole interactions

Answer 33

forces between the positive/negative ends of molecules; present in solid and liquid but are negligible in gas

Question 34

hydrogen bonds

Answer 34

positively charged hydrogen interacts with partial negative on either F, O or N