Chapter 8

Question 1

what are the 3 major types of bonding?

Answer 1

ionic
metallic
covalent

Question 2

what is ionic bonding?

Answer 2

electrostatic attraction (K2ClO4, MgO, NiO)(metal + nonmetal)

Question 3

what is covalent bonding?

Answer 3

electrons are shared (Br2, S8, C6H12O6)(nonmetals)

- for covalent bonding to occur, ionic bonding must be energetically unfavorable

Question 4

what is metallic bonding?

Answer 4

electrons are delocalized (Au, Mg, Cu)

Question 5

what is the octet rule?

Answer 5

atoms gain, lose, or share electrons to achieve a nobel gas configuration

Question 6

what is an ionic bond?

Answer 6

an ionic bond is the electrostatic attraction between positive and negative ions resulting from electron transfer

Na + Cl —> Na+ + Cl-

Question 7

why are noble gas configurations very stable?

Answer 7

attractive forces between ions of opposite charge are maximized
repulsive forces between ions of the same charge are minimized

Question 8

what is lattice energy?

Answer 8

the energy required to separate 1 mole of solid ionics into gas ions

NaCl(s) —> Na+(g) + Cl-(g)

LE parallels melting point/boiling point

Question 9

what is the formula for lattice energy?

Answer 9

LE = Q1Q2/d

charge is more important than distance: +3 > +2 > +1

KCl vs. CaO: CaO has higher LE because CaO has +2,-2 charges while KCl has +1, -1 charges

LiF vs. LiI: same charges….so now you go for the distance: iodine is larger than fluorine so LiF will have higher LE

Question 10

born haber cycle

Answer 10

Hrxn = Hf(metal) + Hf(nonmetal) + IE(metal) - EA(nonmetal) - LE

must be in gas phase*

Question 11

what is a double bond?

Answer 11

pi bond

Question 12

what happens to distance and strength as bond numbers increase?

Answer 12

when there is more than one electron pair between two atoms, the atoms are pulled closer together and the bond length is shorter - bond energy increases

Question 13

EN trend?

Answer 13

electronegativity increases from left to right and from bottom to top

Question 14

ionic or covalent based on EN?

Answer 14

ΔEN < .5 nonpolar covalent

ΔEN > 1.9 - 2.1 ionic

Question 15

state and electronegativity?

Answer 15

if gas or liquid, it tends to be more covalent

if something is a solid it tends to be more ionic

Question 16

dipole moment formula?

Answer 16

Q= μ/r

Question 17

formal charge

Answer 17

valence electrons - #electrons assigned to atom

the most stable structure has the smallest formal charge on each atom - and the most negative charge on the most electronegative atom

Question 18

what are the 3 exceptions to the octet rule?

Answer 18

• odd number of valence electrons (NO, NO2, ClO2)
• central atom has less than an octet (Be or B: BeCl2, BF3)
• central atom has more than an octet below 2nd period, atoms are large, have d orbitals (SF6, PCl5, AsF6-, ClF4+

Question 19

why do we not see compounds of helium or neon but we do see compounds of krypton or xenon?

Answer 19

He and Ne are smaller and have higher IE than Kr or Ze so they are less reactive. Also, Kr and Ze have d orbitals while He and Ne only have s and p

Question 20

the valence electrons have the greatest freedom to move in compounds where atoms are held together by….

Answer 20

covalent bonding