unit 6 - bonding

Question 1

why do bonds form?

Answer 1

system tries to seek the lowest possible energy (because that’s when its the most stable)

unstable separately but more stable when together

concept of bonds is a human invention though - (acc electrostatic forms of attraction, not a line bond)

Question 2

bond energy

Answer 2

energy required to break a chemical bond

• indicates strength of a bonding interaction

Question 3

which bond is the strongest and which bond is the shortest? (single, double, triple)

Answer 3

• triple bond is the shortest but the strongest
• single bond is the longest but the weakest

Question 4

coloumb’s law (formula and the relationships)

Answer 4

E = (2.31 x 10^-19 J x nm)(q1q2/r)

• energy is directly related to the product of the ionic charges
• energy inversely related to the radius

Question 5

Bond energy (BARF)

Answer 5

bonds broken = energy absorbed

bonds formed = energy released

Question 6

bond length and where it’s found

Answer 6

• distance between 2 atoms when potential energy is minimal

found at the lowest point of the potential energy diagram (where it dips)

(potential energy increases drastically after hitting the lowest b/c it is unstable due to the electron electron repulsions)

Question 7

why does electronegativity increase as you go across a periodic table?

Answer 7

stronger effective nuclear charge

Question 8

relationship between electronegativity and bond type

Answer 8

as electronegativity difference increases, bond becomes more ionic

zero = covalent bond

intermediate = polar covalent bond

large = ionic bond

Question 9

why is fluorine the most electronegative element?

Answer 9

• more effective nuclear charge
• need only one electron to complete octet
• smallest atomic radius from all halogens

Question 10

why do noble gases not have electronegativity values?

Answer 10

full outer shell, stable octet

Question 11

why is water a polar molecule?

Answer 11

electron cloud is not distributed symmetrically

Question 12

change in enthalpy formula

Answer 12

ΔH = sum of bonds broken - sum of bonds formed

(energy required to break bonds - energy released when new bonds made)

Question 13

hybridization types

Answer 13

d2sp3 - 6
dsp3 - 5
sp3 - 4
sp2 - 3
sp - 2

Question 14

bond order formula

Answer 14

(# of bonding electrons - # of anti bonding electrons) / 2

Question 15

antibonding normal order vs. special order thing (and which elements follow the special order)

Answer 15

normal pattern:
1
2
1
2

special pattern:
1
2
2
1
(for NE, F, and O)

Question 16

paramagnetic vs. diamagnetic

Answer 16

paramagnetic: unpaired e- attracted towards magnet

diamagnetic: paired e- so no attraction to magnet

molecular orbit theory shows whether paired or unpaired - diamagnetic or paramagnetic

Question 17

how to calculate formal charge

Answer 17

of valence electrons (from the periodic table) - # of bonded electron domains (lines or lone pairs attached)

Question 18

say instead of symmetrical shape

Answer 18

symmetrical distribution of electron cloud

Question 19

delocalization of electron cloud

Answer 19

double bond - causes shorter bond length

Question 20

bonds broken with phase changes?

Answer 20

phase changes do not break or form new bonds!

water is still water even as a gas (water vapor) or solid (ice)

Question 21

why is the radius of F- larger than the atomic fluorine F?

Answer 21

extra electron causes electron electro repulsion causing increased radius