Chemistry - Electrons and ionisation energy

How many electrons can the first four shells hold?

First: 2 second: 8 third: 18 fourth: 32

What is an atomic orbital?

A region of space around the nucleus that can hold up to two electrons with opposite spins.

What shape is an s orbital?

Spherical.

What shape are p orbitals, and why are there three?

A p sub-shell contains three dumbbell-shaped orbitals, called px, py and pz. They point in three directions at right angles to each other, along the x, y and z axes.

Each holds 2 electrons, so a p sub-shell holds 6 electrons in total.

How many orbitals and electrons are in an s sub-shell?

1 orbital, holding up to 2 electrons.

How many orbitals and electrons are in a p sub-shell?

3 orbitals, holding up to 6 electrons.

How many orbitals and electrons are in a d sub-shell?

5 orbitals, holding up to 10 electrons.

Which orbitals fill first?

Electrons fill orbitals with the lowest energy first.

How do electrons fill orbitals of equal energy?

They occupy each orbital singly with parallel spins before pairing.

What is the filling order up to 4p?

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p.

Which electrons are removed first when a transition metal forms an ion?

4s electrons are removed before 3d electrons

How do you write a noble gas electronic configuration?

Replace the inner electron configuration with the preceding noble gas in square brackets, then write the remaining electrons. E.g Calcium is [Ar] 4s² and Iron is is [Ar] 4s² 3d⁶.

What is first ionisation energy?

The energy required to remove one electron from each atom in one mole of gaseous atoms, forming one mole of gaseous 1+ ions.

What equation represents first ionisation energy?

X(g) → X⁺(g) + e⁻

What are successive ionisation energies?

The energies required to remove electrons one at a time from each particle in one mole of gaseous atoms or ions.

What is second ionisation energy?

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions, forming one mole of gaseous 2+ ions.

What equation represents second ionisation energy?

X⁺(g) → X²⁺(g) + e⁻

The hypothetical equation for the 45th ionisation energy of oxygen

X⁴⁴⁺(g) → X⁴⁵⁺(g) + e⁻

But oxygen only has 8 electrons, so it has only 8 successive ionisation energies. After that, there are no electrons left to remove!

Its final one is:

O⁷⁺(g) → O⁸⁺(g) + e⁻