2.1.1 Atomic structure and isotopes

Relative molecular mass (mr)

the weighted mean mass of a molecule in comparison to 1/12th the mass of an atom of carbon-12

Relative formula mass (RFM)

The weighted mean mass of a formula unit compared to 1/12th the mass of an atom of carbon-12

Y axis on a mass spectrometry graph

Percentage abundance

X axis on a mass spectrometry graph

M/z (mass to charge ratio/isotope no)

Victor Is A Daft Duck

Vaporisation, Ionisation, Acceleration, Deflection, Detection

Vaporisation in mass spec

Turns into a gaseous state

Ionisation in mass spec

fires an electron to make it into a positive ion

Acceleration in mass spec

+ ion is accelerated between the positive and negative plates (electric fields)

Deflection in mass spec

Ion reaches this chamber (vacuum), and a magnetic field deflects the +ve particles deflecting the lightest the most

Detection in mass spec

Ions detected by electric current (created when the electrons are transferred from the metal detector)

Number of electrons that can fill the 1st shell

2

Number of electrons that fill the second shell

8

Number of electrons that fill the 3rd shell

18

Number of electrons that fill the 4th shell

32

Formula to work out number of electrons in a shell

2n2

S shape orbital

Single spherical region

P shaped orbitals

Figure 8, 3 individual orbitals, each at 90 degree

Number of electrons in s sub shells

2

Number of electrons in p shells

6

Relative mass and charge of a proton

1 mass and +1 charge

Charge of electron and relative mass

-1 charge and 1/1836 rm

Relative mass and charge of a neutron

1 mass and 0 charge

Atomic number

Number of protons

Mass number

Number of particles (protons and neutrons) in nucleus

Isotope

atoms of the same element with different numbers of neutrons

Ion

a positively or negatively charged atom or (covalently bonded) group of atoms

Relative isotopic mass

The mass of an atom of an isotope in comparison to 1/12th of the mass of a carbon-12 atom

Relative atomic mass (ram)

the weighted mean mass of an atom of an element in comparison to 1/12th the mass of a carbon-12 atom