Molecular Orbital Theory

Question 1

2 1s subshells combine to form a

Answer 1

Sigma molecular orbital

Question 2

New molecular orbital that forms from 2 hydrogens combining is the

Answer 2

Sigma Star * molecular orbital

Question 3

Bonding molecular orbitals energy is ?

Answer 3

Lower

Question 4

Anti-bonding molecular orbitals energy is?

Answer 4

Higher

Question 5

Lower energy orbitals?

Answer 5

Lower the entire energy of our system

Question 6

Bond Order is calculated how?

Answer 6

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

Question 7

How many bonds does a hydrogen molecule have?

Answer 7

1 single bond

Question 8

The # of Atomic Orbitals must be ?

Answer 8

Equal to the # of molecular orbitals energy

Question 9

Answer 9

Hydrogen atom with atomic orbital and sigma star molecular orbital

Question 10

Atomic orbitals are

Answer 10

Non-bonding energy

Question 11

If you have 2 unbonded electrons in atomic orbitals, how many electrons combine to form bonded molecular orbitals ?

Answer 11

Each unbonded electron in an atomic orbital combines with an electron from the other molecule its combining with in the molecular orbital so the number of electrons doubles in the molecular orbital in the center to show how the 2 side atomic orbitals combine in the center. Each atom on a side, combination of the 2 in the center like the combination of these 2 hydrogen atoms

Question 12

Bond order is calculated how?

Answer 12

The number of bonding electrons minus the number of anti bonding electrons then divide that by 2.

For hydrogen we have 2 bonding electrons minus 0 anti bonding electrons so that’s 2 divided by 2 = 1 bond

Question 13

When the sigma bond is formed, the energy does what?

Answer 13

Goes down

Question 14

When the sigma star* bond is formed, the energy does what?

Answer 14

The energy increases to populate the higher sigma star orbital

Question 15

Can 2 helium atoms bond?

Answer 15

No bc they have 2 bonding electrons minus 2 anti bonding electrons = 0 divided by 2 = 0 no bonds

HELIUM EXISTS AS ISOLATED ATOMS

Question 16

Pi and pi*star bonds form from what MO’s- molecular orbitals?

Answer 16

P orbitals

Question 17

Sigma and Sigma*Star bonds form from what MO’s-molecular orbitals ?

Answer 17

S orbitals

Question 18

With bond pictures, we are only looking at the

Answer 18

outer shell for bonding which can be the s orbital or it can be the p orbital, etc. depending on what atoms we are looking at

Question 19

Anti bonding MOs do what do energy?

Answer 19

Increase energy

Question 20

Bonding MOs do what to energy?

Answer 20

Bonding Molecular Orbitals decreases energy, bc it takes energy to bond so it put out energy and its overall energy decreases

Question 21

The anti-bonding orbitals show all the electrons each side atomic has

Answer 21

The center bonding orbitals show how 1 electron of each side comes to join in the center with 1 from the other side and 1 from each box comes to the center first before the 2nd electron from each box comes to the center bonding molecular orbital.

Question 22

If there are 6 atomic orbitals filled, how many molecular orbitals can be filled?

Answer 22

We must have 6 also, these numbers must match

2 electrons can go in each orbital but not all elements will fill all orbitals with 2 electrons

Question 23

Anti bonding electrons still bond into the higher orbit and labeled

Answer 23

Pie star *

Question 24

The first electron that comes out of each orbital make up your?

Answer 24

Bonding electrons

Question 25

The left over electrons that come out of each orbital second are your ?

Answer 25

Anti bonding electrons

Question 26

Your bond order is calculated how?

Answer 26

(Bonding electrons minus anti-bonding e-) divided by 2

Question 27

Diatomic molecules have what type of bond?

Answer 27

Double bond - pie bond

Question 28

In Valence Bond Theory, all electrons are paired which would make it

Answer 28

Diamagnetic (Repelled by a magnet)

Question 29

Is O2 diatomic molecule paramagnetic or diamagnetic?

Answer 29

Paramagnetic (attracted to a magnet) It should be diamagnetic bc all electrons are paired but this is an exception

Question 30

The orbital diagram can be split into 3 parts which are:

Answer 30

Left, right, middle Left shows atom on left for bonding Right shows atom on right for bonding Middle shows molecule bonded

Question 31

Types of intermolecular forces

Answer 31

Dispersion (everything has) Ion-dipole (need an ion) Dipole-dipole (both have to be polar) Hydrogen bonding (can’t have all 4)

Question 32

How does energy increase in an orbital diagram?

Answer 32

Energy increases as you travel up the diagram from bottom to top

Question 33

The bottom 1s sigma orbital is called

Answer 33

A bonding molecular orbital, which has LOWER Energy (at bottom) but GREATER Stability (like the base of a structure is the most stable)

Question 34

The top 1s sigma star* orbital is what type of orbital ? What is its energy and stability like?

Answer 34

Anti-bonding molecular orbital HIGHER Energy (higher up) LESS Stable than the atomic orbitals that formed it (Compared to the 1s atoms that it was formed from)

Question 35

What does the star indicated on the sigma orbitals?

Answer 35

The star indicates that it is anti-bonding (Higher energy, less stable=anti-bonding)

Question 36

Hydrogen is what type of molecule?

Answer 36

Diatomic molecule, comes in pairs H—H 1 double bond 2 atoms, 1 electron each

Question 38

One of the shortcomings of molecular orbital theory is:

Answer 38

It’s inability to account for a triple bond on the nitrogen molecule, N2

Question 39

The length of the bonds is determined by

Answer 39

The # of electrons in the center molecule: the more electrons, the tighter they pull together making the bond shorter and stronger. When there are less electrons the bond is longer and less stable/weaker