5.1 - Electron Structure

Question 1

What are shells and their properties?

Answer 1

• Regarded as energy levels
• Energy increases as shell number increases

Question 2

What are atomic orbitals?

Answer 2

Region around the nucleus that holds up to 2 electrons (no more)

• 4 orbital types: s, p, d, f
• Each orbital type has a different shape

Question 3

Give the features of an s-orbital.

Answer 3

• Spherical shape
• Each shell from n=1 has 1 s-orbital.

Question 4

Give the features of a p-orbital.

Answer 4

• Shape: dumb-bell
• 3 separate p-orbitals (p_x, p_y, p_z) all at right angles to each other
• From n=2, each shell has 3 p-orbitals
• Greater the shell number n, further from nucleus the p-orbital is.

Question 5

Give the features of d & f orbitals.

Answer 5

• From n=3, each shell has 5 d-orbitals4
• From n=4, each shell has 7 f-orbitals

Question 6

How does orbital filling work?

Answer 6

• Fills in temrms of increasing energy order
• Each new sub-shell that is added, has a higher energy

e. g. the 2s orbital in n=2 has less energy than the 2p
* Beware, the highest energy level in n=3 overlaps the lowest in n=4, therefore 4s fills before 3d

Question 7

What are the characteristics of electron spin diagrams?

Answer 7

• Each arrow represents an electron
• 2 electrons in a box must face the opposite direction
• When filling sub-shells, each orbital is filled singly before electrons are paired
• Each box is an orbital

Question 8

What is the sub-shell filling order?

Answer 8

1s 2s 2p 3s 3p 3d 4s 4p

e.g Krypton: 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶

Question 9

Explain how to use the write the shorthand electron configuration.

Answer 9

• Use the nearest previous noble gas’s in square brackets, and write the remaining electrons normally.
  e. g. Li: 1s²2s¹ Shorthand: [He] 2s¹

K: 1s²2s²2p⁶3s²3p⁶4s¹ Shorthand: [Ar] 4s¹

Question 10

Describe the make up of the periodic table in terms of sub-shells.

Answer 10

• Periodic table divided into blocks corresponding to their highest energy level

1^st 2 groups: s-block

Centre 10 blocks: d-block (transition metals)

Last 6 groups: p-block

Bottom 2 periods: f-block