Atomic Structure

Nucleus

Nucleus

Where most of the mass is concentrated

Very small

Contains protons and neutrons

Electrons

Make up most of the volume

orbits the nucleus in shells

Proton relative charge

+1

proton relative mass

1

neutron relative charge

0

neutron relative mass

1

electron relative charge

-1

electron relative mass

1/2000

Ions

different number of protons or electrons

negative ion

gained electrons to gain full outer shell and become a more stable ionic compound

positive ion

lost electrons to gain a full outer shell of electrons and become more stable ionic compound

isotope

elements with the same number of protons and electrons but a different number of neutrons

Vaporisation

sample is ionised so it can travel through TOF mass spectrometer

Ionisation

The sample is pushed through a nozzle making a high pressure jet. A high voltage is passed through causing the loss of an electron. A gaseous positively charged sample is produced = electrospray ionisation

Acceleration

The positive ions are passed through an electric field. Particles with lower mass/charge (m/z) ratio will accelerate quicker

Ion Drift

The positive ions are passed through an electric field. Particles with a lower (m/z) ratio will accelerate quickly

Detection

Ions are detected as electrical current is made when particle hits the plate. Particles with lower m/z reach the detector first as they travel faster

Relative atomic mass

the average mass of an atom of an element when measured on a scale where the mass of an atom of C12 is exactly 12

Relative isotopic mass

the mass of an atom of an isotope of an element is measured on a scale where the mass of C12 is exactly 12

Relativive molecular mass

the average mass of a molecule when measure on a scale where the mass of an atom of C12 is exactly 12

m/z

the mass of an isotope/charge

relative atomic mass calculation

= (abundance A x m/z A) + (abundance B x m/z B) / total abundance

Which d-block elements behave differently

chromium and copper

how does chromium behave differently

an electron moves from the 4s orbital into the 3d orbital to create a more stable half full or full subshell respectively

Ionisation energy

the minimum amount of energy to remove 1 mole of electrons from 1 mole of atoms in the gaseous state

Shielding

the more electron shells between the positive nucleus and negative electron that is beiung removed, the less energy required. There is weaker attraction.

Atomic size

Bigger the atom = further away the outer electrons from the nucleus. The attractive force between the nucleus and outer electrons reduces meaning it is easier to remove the electrons

Nuclear charge

the more protons in the nucleus = the bigger the attraction between the positive nucleus and the negative outer electron = more energy to remove the electron.

Successive ionisation

removal of more than 1 electron from the same atom

Group 2 1ST ionisation trends

ionisation energy decreases as we go down the group

The atomic radius increases = the outer electrons are further away from the nucleus. the attractive force is weaker. the energy needed to remove the electron decreases

Shielding increases = more shells between the nucleus and the outer shell. the attractive force is weaker. the energy needed to remove the electron decreases.

Niels Bohrs model is correct = evidence for shells

period 3 1st ionisation energy trends

ionisation energy increases across a period

increases nuclear attraction because there is an increasing number of protons in the nucleus

the shielding is similar and the distance from nucleus decreases

the ionisation energy increases as more energy is needed to remove an electron