Molecular shape and bonding

Question 1

Ionic Bonding

Answer 1

metal and non metal

transfer of electrons

Question 2

Covalent Bonding

Answer 2

non metal and non metal

stare of electrons

Question 3

Metalic Bonding

Answer 3

metal and metal

electrons pooled

Question 4

Why do chemical bonds form?

Answer 4

because they lower the potential energy between the charged particles that constitute atoms.

Question 5

What is Lewis Theory?

Answer 5

The valence electrons (outer) are held most loosely and hence used in bonding.

Elements in same column have same properties bc they have the same number of valence electrons.

Question 6

What is the Octet Rule?

Answer 6

8 - is the most stable configuration for most atoms.

Atoms with transfer/share electrons to reach this.

Question 7

Ionisation energy…

Answer 7

energy required to remove the electron.

Question 8

Elements with low ionisation energies are..

Answer 8

electropositive.

Question 9

Elements that readily acquire electrons are…

Answer 9

electronegative.

Question 10

Lewis theory was not good at…

Answer 10

explaining other data e.g. the rigidity of carbon-carbon double bonds.

Question 11

heisenberg uncertainty principle says…

Answer 11

The position and speed of electrons are complementary.

If we know one accurately, we can’t know the other accurately.

Question 12

How are each orbits represented according to mathematical calculations?

Answer 12

1s - a small sphere
electron can be found anywhere

2s - a larger sphere
contains a node

Question 13

What is the radial node?

Answer 13

Found in 2s orbital - a region where the probability of finding the electron falls to zero.

Question 14

De Broglie

Answer 14

electrons have both particle-like and wave-like properties.

Question 15

The node is a result of…

Answer 15

the wave-like behaviour of electrons.

Question 16

Imagine plucking a guitar string…

Answer 16

Wave function (+) is the region above the rest position and (-) is below it.

Question 17

Where is the node on a guitar string?

Answer 17

The region where the amplitude (maximum displacement) of the standing wave is zero.

Question 18

What are the shapes of the p-orbitals?

Answer 18

Dumbbell shaped.

They have a nodal plane that cuts the dumbbell into two lobes.

Question 19

There are three degenerate p atomic orbitals. What does this mean?

Answer 19

They all have the same energy.

2px orbital
2py orbital
2pz orbitals

Question 20

Energy of a 2p atomic orbital is ……… than the energy of the 2s atomic orbital

Answer 20

greater than

Question 21

Two main theories to describe a covalent bond:

Answer 21

Molecular orbital theory
- atomic orbitals are combined to make MO’s.

Valence-bond theory
- electrons within the molecule remain in the atomic orbitals, but we don’t know in which atomic orbital

Question 22

Addition of wave functions of two atoms leads to…

Answer 22

a bonding molecular orbital

Question 23

Subtraction of wave functions of the two atoms leads to..

Answer 23

an anti-bonding molecular orbital

anti just means its a higher in energy.

Question 24

What is a rule of molecular orbital theory?

Answer 24

If you put in 2 molecular orbitals, you must get 2 out.

Question 25

molecular orbitals for H1...

Answer 25

H2 is made of 2 1s orbitals. 1S a + 1S b one is anti bonding (higher energy) and the other is a bonding.

Question 26

Where can the electrons be found in an anti-bonding orbital and in a bonding?

Answer 26

anti bonding - anywhere but the node bonding - most likely between the nuclei.

Question 27

In summary | combining two 1s hydrogen atomic orbitals results in...

Answer 27

2 new molecular orbitals with sigma symmetry. one is anti bonding the other is bonding

Question 28

What happens when we combine to 2p atomic orbitals and they bind end on:

Answer 28

sigma anti bonding with 3 nodes sigma bonding with 2 nodes

Question 29

2p atomic orbitals can also bind...

Answer 29

side on pi' anti-bonding with 2 nodal planes pi' bonding with 1 nodal plane

Question 30

Which is stronger - a pi bond or a stigma pond?

Answer 30

stigma

Question 31

End on end overlap gives a greater...

Answer 31

overlapping of p atomic orbitals

Question 32

What is Hybridisation?

Answer 32

where various combinations of orbitals are used to make new hybrid orbitals in order to simplify the maths.

Question 33

What would we get if we mixed 2s and 2p orbitals together? What does this tell us?

Answer 33

sp3 orbitals they are degenerate = same energy and same shape. made up of: 1/4 S and 3/4p

Question 34

How do the sp3 orbitals arrange themselves?

Answer 34

in a spatial arrangement - to minimise electron repulsion. gives a bond angle C-H of 109.5 tetrahedral

Question 35

Shape for the bond angle 180 d 120 d 109.5 d

Answer 35

180 - linear sp hybridisation 120 - trigonal planar sp2 109.5 - tetrahedral sp3

Question 36

How to know what the hybridisation is?

Answer 36

2 electron groups - sp 3 groups - sp2 4 groups - sp3 double bond counts as one. lone pair counts as one electron group.

Question 37

All single bonds

Answer 37

are sigma bonds

Question 38

all double bonds have

Answer 38

one sigma and one pi bond

Question 39

all triple bonds have

Answer 39

one sigma bond and two pi bonds

Question 40

Why is hybridisation important?

Answer 40

because it relates to drug structure. drug structure is controlled by functional groups which s related to valency and hybridisation.