2.1.1: Atomic structure Flashcards
Ion
A charged particle; an atom that has gained/lost electrons.
Relative formula mass (not required)
The number of times the mean mass of one molecule of the molecular compound is heavier than 1/12.0, the mass of one atom of carbon-12.
Relative atomic mass (Aᵣ)
The weighted mean mass of an atom of an element relative to 1/12th the mass of an atom of carbon-12.
Relative isotopic mass
The mass of an isotope relative to 1/12th the mass of an atom of carbon-12.
Degenerate
having the same energy
Orbital
A probability region for an electron.
First ionisation energy
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous unipositive cations.
Positive ion
Cation
Negative ion
Anion
Electron relative mass
1/1840
Neutron relative mass
1
Proton relative mass
1
Uses of Mass Spectrometry
- Determination of (relative masses/abundances of) isotopes
- Determination of successive ionisation energies
- Determination of molecular structure
Mass Spectrometry steps
1) Vaporise sample
2) Ionise sample
3) Accelerate sample
4) Deflect through magnetic field according to mass/charge ratio
5) Detect the ions
Why is the ‘charge’ in the mass-charge ratio always the same?
- Electron gun knocks out outermost electron
- Therefore the charge is always +1
- So the mass determines the deflection
Isotopes
Atoms of the same element with the same number of protons and electrons but different numbers of neutrons and thus different masses.
Difference between ‘relative formula mass’ and ‘relative molecular mass’
- RFM: refers to compounds with giant structure
* RMM: refers to simple molecules
How to calculate RFM or RMM
(No. of atoms of element x Aᵣ of element) + (No. of atoms of element x Aᵣ of element) continue as necessary
How to calculate Aᵣ from relative isotopic abundance
(Mass number x abundance %) + (Mass number x abundance %)
