5.1 - Electron structure Flashcards
What is electron configuration?
The arrangement of electrons in an atom
Describe what an electron is
A cloud of negative charge which takes the shape of the orbital occupied by the electron
How many electrons can the first four shells hold? 2n²
1 = 2
2 = 8
3 = 18
4 = 32
What is the link between the distance of a shell and the nucleus to the energy of the shell?
The further away a shell, the weaker the attraction to the nucleus, and the higher its energy level
What is an atomic orbital?
A region around the nucleus that can hold up to two electrons, with opposite spins
What are the four types of orbitals?
- S
- P
- D
- F
What is a subshell?
All of the orbitals of the same type in the same shell
What shape is a s orbital?
How many subshells and the number of electrons?
A sphere, one subshell - 2 electrons
What shape is a p orbital?
How many subshells and the number of electrons?
A dumbbell, three subshells - 6 electrons
How many subshells and electrons are in the d orbitals?
Five subshells - 10 electrons
How many subshells and electrons are in the f orbitals?
Seven subshells - 14 electrons
What orbitals are present in the energy shells (1 to 4)?
1: S
2: S P
3: S P D
4: S P D F
In what order do orbitals fill? and write it out
They fill in order of increasing energy:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f
Why does the 4s subshell fill up before the 3d subshell?
- The 3d sub-shell is at a higher energy level than the 4s sub-shell
- Since orbitals fill in order of increasing energy
- The 4s sub-shell fills up before the 3d sub-shell
How and why do electrons pair with opposite spins?
- Electrons are negatively charged and repel one another
- Their spin can either be up or down
- Two electrons in an orbital must have opposite spins
- The opposite spins help to counteract the repulsion between the negative charges of the two electrons
Why are orbitals with the same energy occupied singly first?
- It prevents any repulsion between paired electrons until there is no further orbital available at the same energy level
Should the electron configuration be shown in shell order or filling order?
Shell order, so 3d would be written first, followed by 4s, even though 4s fills up first
When writing the electron configuration shorthand, what group is used?
Noble gases
e.g Li = 1s² 2s¹ = [He] 2s¹
Does the 4s sub-shell empty before the 3d sub-shell?
Yes
