C3 : Electrons and orbitals

Describe electron struture in terms of shells, subshells and atomic orbitals

electrons are arranged around the nucleus in shells, sub shells and orbitals

shells :

• represent main energy levels of an atmosphere denoted by n = 1, 2, 3, 4, …

• electrons further from the nucleus have higher energy

subshells :

• each shell contains subshells (s, p, d, f)

atomic orbitals :

• regions where electrons are likely to be found

• each orbital can hold 2 electrons with opposite spin

Express the electronic configuration of …

Express the electronic configuration of …

Express the electronic configuration of …

Express the electronic configuration of …

Express the electronic configuration of …

Describe molecular orbitals (σ and π bonding)

molecular orbitals form when atomic orbitals overlap

sigma (σ) bonds :

• head-on overlaps of orbitals

• electron density lies directly between nuclei

• strongest type of covalent bond

• every single bond has a σ bond

pi (π) bonds :

• side-on overlaps of orbitals

• electron density lies above and below the body axis (plane)

• weaker than σ bonds

• present 1+ bonds (e.g. double and triple bonds)

Describe orbital hybridisation theory

the mixing of atomic orbitals to form new hybrid orbitals explaining the bonding and molecular shape

sp :

• produces 2 hybrid orbitals

• bond angle = 180°

• example: ethyne

sp² :

• produces 3 hybrid orbitals

• bond angle = 120°

• example: ethene

sp³ :

• produces 4 hybrid orbitals

• bond angle = 109.5°

• example: ethane

Explain how orbital hybridisation theory contributes to the shape and bonding in molecules

it explains:

• molecular shape - determines the arrangement of bonding pairs around an atom

• bond formation - hybrid orbitals overlap to from strong σ bonds

• bond angles - predicts experimental bond angles accurately

What is the orbital hybridisation state of this carbon atom

What is the orbital hybridisation state of this carbon atom

What is the orbital hybridisation state of this carbon atom

What is the orbital hybridisation state of this carbon atom

What is the orbital hybridisation state of this carbon atom