2.2.1 Subshells and Orbitals

Question 1

What are the uses of quantum numbers (n)?

Answer 1

Each shell has a different quantum no., n - the principal quantum number indicates this. The larger ‘n,’ the further the shell is from the nucleus, the higher the energy level. This represents the relative overall energy of each orbital.

Question 2

What is the order that these shells fill in? Why does this work? How many electrons are in each shell up to 4 inclusive?

Answer 2

This works because it shows the order of energy levels - electrons occupy sub-shells in order of increasing energy levels.
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
The coefficients correspond to the shell number - 2s and 2p are both in the same shell. Each shell is composed of a number of atomic orbitals.
Electron count up to shell 4 inclusive is 2(shell no.)^2

Question 3

What is a ‘shell’?

Answer 3

A group of atomic orbitals with the same principal quantum number, n. Also known as main energy level.

Question 4

What is the ‘planetary electron’ idea? Why is this not accepted?

Answer 4

Electrons orbit the nucleus like planets. This is false as electrons are not solid particles and so only have a probability of being found in x place.

Question 5

What is the max. no of electrons each atomic orbital can hold?

Answer 5

Two electrons of opposite spin.

Question 6

What shape is the s orbital and how many electrons can it hold?

Answer 6

Spherical shape, holds two electrons. Each shell contains one s-orbital.

Question 7

Who discovered orbitals and what supported their idea?

Answer 7

Plum pudding Nobel prize Bohr, said properties of elements was down to electrons, which existed at fixed distances from the neuc. Calculating ionisation energy values for removing successive electrons supported this idea.

Question 8

What is a p orbital?

Answer 8

3D dumbbell shape, with dumbbell at center of nucleus. Px, Py and Pz are sub shells at right angles and can hold a collective maximum number of 6 electrons (2x3).

Question 9

What is a d orbital?

Answer 9

From n=3 upwards, each shell has 5 d orbitals - 2x5=10 max. no of electrons.

Question 10

What is an f orbital?

Answer 10

From n=4 upwards, each shell has 7 f orbitals - 2x7=14 max. no of electrons.

Question 11

What are box diagrams?

Answer 11

Called 'electrons in boxes.' Each box represents an orbital, = up arrows and down arrows. Electrons don't repel each other because of this spin.
F - 7 boxes/orbitals, 14 electrons
D - 5 boxes/orbitals, 10 electrons
P - 3 boxes/orbitals, 6 electrons
3 - one box/orbital, 2 electrons

Question 12

What are orbitals?

Answer 12

Things that plot where electrons are most likely to be found - electrons are only particles and waves.