Week 2 Module 1

Question 1

What word is interchangable with orbital?

Answer 1

Wave function.

Question 2

What is the 1s orbital and si1s^2 orbitals relationship with 0?

Answer 2

They almost reach 0 but only end up approaching for infinity.

Question 3

What do we have to think about when we think about probability density?

Answer 3

Shells - the probability of finding an electron in a particular shell.

Question 4

What is the thickness of an electron shell?

Answer 4

Δr, therefore thickness increases with r.

Question 5

Explain radial probability density of si1s^2.

Answer 5

r=o being 0 chjecks out as r=0 is like a tiny dot and vry close to the nucleus. Prob is also around 0 when r is very large. Inbetween, there is a curve with a maximum probability. “There is a maximum probability point that is somewhat away from the origin

Question 6

How many nodes are there in the 2s orbital? What does this mean?

Answer 6

There is 1 nod, - there is a more complex 1d and 2d wave.

Question 7

What does the graph of the 2s orbital look like?

Answer 7

We start off at a maximum point which decreases, touches 0 at the node, and goes in the negative region of the amplitude where it curves back and approaches 0 as r increases.

Question 8

Explain the radial probability density of 2s orbital.

Answer 8

At the node, the wave function amplitude = 0, si2s = 0 at node.
Also 0 at origin and basically 0 at a large r.

Question 9

Where is the most probable place to find electrons in a 2s radial probability density?

Answer 9

Around 0.3. The probability is actually higher than for 1s orbital.

Question 10

What is energy directly proportional to in shells?

Answer 10

The number of nodes. More nodes = higher energy = more complex.

Question 11

Where can atoms be in a radial probability density?

Answer 11

Anywhere above 0 , just at different probabilities.
Concept exists because of the wave characteristic (?)

Question 12

What is the 3D shape of the 3s orbital and what does it mean?

Answer 12

Spherical meaning no matter what firection you go the graph stays the same.

Question 13

How many nodes does the 3s orbital have?

Answer 13

2 nodes, making it more complex than the 2s orbital. - refer to page 10 for the radial probability density.

Question 14

What increases the size of an orbital?

Answer 14

n.

Question 15

Are all orbitals spherically symmetrical?

Answer 15

No.

Question 16

What does the subscript z in 2pz signify?

Answer 16

That it is orientated on the z axis/ in the z direction.

Question 17

How many lobes does dyz orbital have?

Answer 17

4 lobes seperated by 2 nodal planes - amplitude of 0.

Question 18

What are 3D blobs called?

Answer 18

Nodes - regions of a 3D wave.

Question 19

What do you get if you square the wavefunction of a non-spherical orbital?

Answer 19

It still gives the probability.

Question 20

What happens to the shape of a non-spherical orbital if you square it?

Answer 20

It changes the lobe shape slightly but general features remain.

Question 21

How many P orbitals are there and how many D orbitals are there?

Answer 21

3 and 5.

Question 22

What is the quantum number n?

Answer 22

The principle QN as it determines the size of the orbital and is involved in the other numbers l and m. Can be 1,2,3… etc. n is the number in front in 1s, 2p, 3d etc.

Question 23

What does n determine?

Answer 23

The energy. Therefore 2p and 2s have the same energy.”

Question 24

n example.

Answer 24

En ∝ -(1/n^2)

Question 25

What does λ = n(/h??)/(mxu) show?

Answer 25

That electrons have both wavelength and momentum. (m x u)

Question 26

What is the quantum number for orbital angular momentum?

Answer 26

l. It is related ti the principal number n. Called the azimuthal quantum number.

Question 27

What values can l take on?

Answer 27

Any value between 0 and n-1.

Question 28

What values can the Magnetic Quantum Number m take on?

Answer 28

Related to l in such a way that m can be = -l, ..., 0, ..., l.

Question 29

What is m if l = 1?

Answer 29

m = -1, 0 , +1 (3 x 2p orbitals)

Question 30

What are the 3p orbitals on an axis?

Answer 30

x, y, and z.

Question 31

What do the values of l mean for the type of orbital?

Answer 31

l=0 is s, l=1 is p, l=2 is d and l=3 is f

Question 32

What do the restrictions on the values of l and m do?

Answer 32

Make some orbitals impossible. eg. 1p, 2d, 3f are impossible as l must be less than n.

Question 33

Explain the 3d orbitals also with QN.

Answer 33

n=3, l can be 2 (d orbitasls). Think of 3d/s as spherical but no nodes. When l = 2, -2<=m<=2. Therefore there are 5 different 3d orbitals. 3 are drawn using different xyz axis, one is dx^2-y^2 and the other is dz^2. 5 possible values correspond to 5 orbitals.

Question 34

What is the attractive potential between proton and electron?

Answer 34

V(r) = -e^2/(4πε(o)r) or v(r)∝-1/r. The closer to the nucleus the electron is, the higher electron potential. (wave property prevents anything from happening.)

Question 35

Ĥψ = Eψ

Answer 35

Ĥψ is kinetic potential.

Question 36

t does solving the wave equation for a paticular potential energy function tell us?

Answer 36

1. The wavefunction. 2. Value for the energy E.

Question 37

What is quantisation?

Answer 37

Quantization is the process of converting continuous, infinite values into a smaller set of discrete, finite values

Question 38

Explain transition between levels?

Answer 38

Electrons can jump to different levels.

Question 39

What does electron transition between levels require?

Answer 39

Energy that is equal to the difference in the energy levels. Goes up with the absoption of a photon and reemits it when it goes back down.

Question 40

Explain allowed energy.

Answer 40

En = -(2 x π^2 x m x e^4)/(h^2 x n^2). Can be simplified with the Rydberg constant 2.18 x 10^-18 to be -2.18 x 10^-18 x n^2. This equals -Eᴿ 1/n^2