Wavefunctions

Question 1

What is the equation for a wavefunction?

Answer 1

Normalisation constant (A) x angular x radial x exponential

Question 2

What does the negative exponential decay represent?

Answer 2

The dependence of the wavefunction from the distance to the nucleus

Question 3

What is the angular part of the wavefunction?

Answer 3

It depends on the direction

Question 4

What is the radial part of the wavefunction?

Answer 4

It depends only on the distance to the nucleus r and not on the direction

Question 5

What value is used if either of the radial or angular parts are missing?

Answer 5

1

Question 6

What does the angular part describe?

Answer 6

Shape and orientation

Question 7

Which quantum number is the number of nodes?

Answer 7

ι

Question 8

How many angular nodes does a 1s orbital have?

Answer 8

ι = 0

s orbitals are spherical and have no direction dependence

Question 9

How many angular nodes does a 2p orbital have?

Answer 9

ι = 1

They have different orientations in space

Question 10

How many angular nodes does a 3d orbital have?

Answer 10

ι=2

Has 2 planes

Question 11

What does the radial part describe?

Answer 11

the effective size of the orbital

Question 12

How do you calculate the number of radial nodes?

Answer 12

The total number of nodes (n-1) minus the number of angular nodes ι

Question 13

Why don’t you look at A or the exponential decay in the wavefunction equation?

Answer 13

They are effectively constant

Question 14

How many radial nodes does a 1s orbital have?

Answer 14

0

Question 15

How many radial nodes does a 2s orbital have?

Answer 15

1

Question 16

How many radial nodes does a 3s orbital have?

Answer 16

2

Question 17

The number of radial nodes…

Answer 17

Increases with n

Question 18

What is electron density proportional to?

Answer 18

The distance from the nucleus

Proportional to the number of points at which the electron can be at a particular value of r

Question 19

What is radial probability function?

Answer 19

Electron density at a distance r from the nucleus is proportional to 4πr²φ²

Question 20

Where in an s orbital is there the most electron density in R²?

Answer 20

The outermost lobe of the orbital

Question 21

Do 2p orbitals have any radial nodes?

Answer 21

No

Question 22

Do 2p orbitals have any angular nodes?

Answer 22

Yes

When x=o, y=o or when z=o

Question 23

When is there a change of phase?

Answer 23

When you cross a node

Question 24

What do orbital energies depend on for multi electron atoms?

Answer 24

Quantum numbers n and ι

Question 25

What do orbital energies depend on for the hydrogen atom?

Answer 25

n only

Question 26

Why do the orbital energies for H2 only depend on n?

Answer 26

2s and 2p orbitals are degenerate, they have the same quantum number
3s, 3p and 3d orbitals are also degenerate orbitals

Question 27

What does absorption do?

Answer 27

Promotes an electron from a lower to an upper energy level

Question 28

What does emission do?

Answer 28

Allows an electron to decay from an upper to a lower level

Question 29

What do you need to remember to draw when you draw a contour plot?

Answer 29

• Nucleus (labelled)
• Different phase - either by colour or by sign
• Radial and angular nodes (labelled)
• Axis drawn and labelled