from workshops

Question 1

How do you convert gmol^-1 masses to the mass of a single atom in kg?

Answer 1

multiply by the atomic mass unit

Question 2

equation for KE rearranged for v?

Answer 2

sqrt (2KE/m) = v

Question 3

equation to convert wavenumbers to energy

Answer 3

E(J) = hc v(cm^-1)
v = overlined

Question 4

1eV in J

Answer 4

1.602 X10^-19 J

Question 5

what is h?

Answer 5

Planck’s constant

Question 6

what is E_a?

Answer 6

antibonding energy

Question 7

what is E_b?

Answer 7

bonding energy

Question 8

what is S?

Answer 8

bond length overlap

Question 9

electron configuration of C?

Answer 9

[1s2] (2s)2 (2p)2 = 4e-

Question 10

electron configuration of N?

Answer 10

[1s2] (2s)2 (2p)3 = 5e-

Question 11

list all of the MO upto 2p for a molecular energy level diagram, starting from the bottom

Answer 11

1σ, 2σ, 3σ, 4σ, 1π, 5σ, 2π, 6σ

NOTE 1π and 5σ can be the other way around

Question 12

how many e- can a pi orbital hold?

Answer 12

4 (2 from each atom)

Question 13

electron configuration of H?

Answer 13

1s1

Question 14

electron configuration of He?

Answer 14

1s2

Question 15

electron configuration of Li?

Answer 15

[1s2] 2s1

Question 16

electron configuration of Be?

Answer 16

[1s2] 2s2

Question 17

electron configuration of B?

Answer 17

[1s2] 2s2 2p1

Question 18

electron configuration of O?

Answer 18

[1s2] 2s2 2p4

Question 19

electron configuration of F?

Answer 19

[1s2] 2s2 2p5

Question 20

Mr of He?

Answer 20

4.003

Question 21

Mr of Li?

Answer 21

6.94

Question 22

Mr of Be?

Answer 22

9.012

Question 23

Mr of B?

Answer 23

10.81

Question 24

Mr of C?

Answer 24

12.011

Question 25

Mr of N?

Answer 25

14.007

Question 26

Mr of O?

Answer 26

15.999

Question 27

Mr of F?

Answer 27

18.998

Question 28

how is the number of molecular orbitals related to the number of parent atomic orbitals?

Answer 28

same amount of MOs as parent atomic orbitals

Question 29

How can the order of 1π and 5σ change?

Answer 29

upto N the order is 1π first then 5σ (so for B2, C2, and N2) then the order switches to 5σ then 1π for O2 and F2

Question 30

What does higher bond order mean?

Answer 30

higher bond energy and smaller bond length (so stronger bond)

Question 31

when calculating the bond order of an ion, where are the electrons lost from first?

Answer 31

the HOMO, highest occupied molecular bonding orbital

Question 32

in a 2s 2p MO energy diagram, which AO partially contribute (dotted line) to which orbitals?

Answer 32

2p contributes to 4σ* and 3σ | 2s contributes to 6σ* and 5σ

Question 33

spin multiplicity equation?

Answer 33

(n+1) when n = no. of unpaired e- e.g. if 2 unpaired e- then the spin multiplicity = spin triplet (1 unpaired e- from each)

Question 34

what is a spin triplet?

Answer 34

when two electrons in parallel orbitals have parallel (the same) spins

Question 35

what may cause the orbitals from each atom to be in different positions to each other?

Answer 35

electronegativity: the more electronegative atom will be at a lower energy because in the bonding orbital the more electronegative atom makes a greater contribution; therefore the antibonding orbital will be closer to the more electronegative atom

Question 36

what is the difference between alpha and Beta?

Answer 36

``` alpha = spin up beta = spin down ```

Question 37

what is Hund's rule?

Answer 37

in its ground state an atom adopts a configuration with the greatest number of unpaired electron spins

Question 38

what is ϕ?

Answer 38

the rotation coordinate