2.2.1 Electron Structure

how are electrons arranged?

orbit the nucleus at different energy levels called shells

what is a shell?

a group of atomic orbitals which have the same principle quantum number, can be split up into separate subshells: s,p,d,f

what is an orbital?

a region around the nucleus that can hold up two electrons with opposite spins

what shape is an s orbital?

spherical

what shape is a p orbital?

dumbell

what is the general formula for the number of electrons in each sub-shell?

2n²

how many s orbitals make up the s sub-shell?

1

how many electrons can an s subshell hold?

2 x 1 = 2 electrons

how many p orbitals make up the p sub-shell?

3

how many electrons can a p subshell hold?

2 x 3 = 6 electrons

how many d orbitals make up the d sub-shell?

5

how many electrons can a d subshell hold?

2 x 5 = 10 electrons

how many f orbitals make up the f sub-shell?

7

how many electrons can an f subshell hold?

2 x 7 = 14 electrons

what are the rules in which electrons fill shells? (3)

1. lowest energy orbital is filled first,

2. electrons occupy orbitals singly before pairing up,

3. no single orbital holds more than 2 electrons

how to electrons pair up?

with opposite spins so atom is as stable as possible, represented by opposite arrows ↑↓

how to electrons fill orbitals?

• electrons start from shells with the lowest energy

• exception = 4s fills before 3d as it has a lower energy level

• for orbitals with the same energy, occupation singly before pairing

what do blocks of the periodic table correspond to?

what orbital the highest energy electron is in