M2, B2 Electron Arrangement & Ionisation Energies

Mass: Proton= 1 Neutron= 1 Electron= 1/2000 Charge: Proton= +1 Neutron= None Electron= -1

Electrons have a negligible mass due to it being so small

Because atoms have no overall charge

• Which element it is • Where it is in the periodic table

Atoms of the same element with different numbers of neutrons (and therefore different masses)

The mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12. (This is the mass of a single atom, so it will be a whole number)

The average mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12. (Atomic mass takes all of the isotopes of the element into account)

(mass x abundance) + (mass x abundance) Divided by the total abundance %

1= two electrons 2= 8 electrons 3= 18 electrons 4= thirty two electrons

A region within an atom that can hold up to 2 electrons with opposite spins

The first shell has an s-sub shell and so only contains a total of 2 electrons (1 s-orbital)

Shell number 2 is made up of s and p sub shells, so it has 1s orbital and 3 p orbitals. Its total is therefore 8 electrons

Shell 3 contains s, p and d subshells and so has 1 s orbital, 3 p orbitals and 5 d orbitals. Total electron count is 18 (2x1)+(2x3)+(2x5)= 18

The fourth shell contains s, p, d and f subshells, and so has: 1 s orbital (2) 3 p orbitals (6) 5 d orbitals (10) 7 f orbitals (14) Total= 14+10+6+2= 32 electrons.

When transition metals form ions, they lose electrons from the 4s orbital before the 3d, even though they’re in the reverse order in the sequence.

The energy that is required to remove one (mole of) electron(s) from one mole of GASEOUS atoms. E.g- Cl (g)— Cl+ (g) + e-

• There is a general increase across the period. • There are more protons in the nucleus (so a greater nuclear charge). • But the outer electrons are in the same shell (the shielding is the same). • So there is an increasing nuclear attraction for the outer electron. • The outer electron is held closer to the nucleus (so atomic radius decreases). • So more energy is required to remove the outer electron.

The electron between groups 2&3 is from a different subshell, the p subshell has a higher energy level than the s subshell. But its a higher energy level in 2 because electrons are fully paired so i.e drops down to group 3. Electron repulsion occurs between 5 and 6 where in group 6 electrons are fully paired, but in group 5, not all electrons are paired.

• More shells so outer electron is further from the nucleus • More shielding (where inner electrons repel outer shell electrons) • Causes a decrease in nuclear attraction on outer electron • The number of protons increases, but this is far outweighed by the increased shielding • less energy is required to remove the outermost electron (outer electrons are held less tightly)

A measure of the energy required to remove each electron in turn from an atom.

• Number if protons remaining is the same but the proton to electron ratio is increasing (makes it harder to remove an electron). • So there is more nuclear attraction of remaining electrons.

Successive i.e is the process of removing electrons from the SAME atom starting from the OUTER electrons and working inwards. The data is used to tell us the IDENTITY of an atom.