Atomic Structure
Subatomic Particle Relative Mass Relative Charge Location in atom
Proton 1 ˖1 Nucleus
Neutron 1 0 Nucleus
Electron 1/1840 ˗1 Energy Levels
Atomic Number: Same as number of protons in the nucleus of an atom
Mass number: Total number of protons and neutrons in the nucleus of an atom
RAM: Average (weighted mean) mass of an atom of an element relative to one-twelfth the mass of
an atom of carbon twelve.
RIM: Replace ‘atom’ with ‘isotope’ RMM: replace ‘atom’ with molecule RFM: replace ‘atom’ with
‘formula’
RAM = Σ( mass of isotope x relative abundance)
Σ(relative abundance)
Mass spectrometry
It is assumed that all the ions in a mass spectrum have a single positive charge
Y axis; Relative Abundance Horizontal axis; mass/ mass to charge ratio/ m/z
Diatomic elements e.g. chlorine have 5 peaks
Molecular ion peak: Last major peak/ RMM
Base peak: Peak with the highest relative abundance
A molecular ion is an ion formed from the removal of an electron from a molecule.
Electronic Configuration
Orbital: a region within an atom that can hold up to two electrons with opposite spin
S subshell: one ‘s’ orbital
P subshell: three ‘p’ orbitals D subshell: five ‘d’ orbitals
Type Energy Level Number of this Maximum Shape
type of orbital in number of
a sub shell electrons
s 1 1 2 Spherical
p 2 3 4 Dumbbell
d 3 5 10 Not required
f 4 7 14 Not required
Subshells fill in the following order: 1s,2s,2p,3s,3p,4s,3d,4p
But should be written as 3p, 3d, 4s, 4p/ Electrons are lost as: 4p, 4s, 3d, 3p, 3s, 2s, 1s
Subatomic Particle Relative Mass Relative Charge Location in atom
Proton 1 ˖1 Nucleus
Neutron 1 0 Nucleus
Electron 1/1840 ˗1 Energy Levels
Atomic Number: Same as number of protons in the nucleus of an atom
Mass number: Total number of protons and neutrons in the nucleus of an atom
RAM: Average (weighted mean) mass of an atom of an element relative to one-twelfth the mass of
an atom of carbon twelve.
RIM: Replace ‘atom’ with ‘isotope’ RMM: replace ‘atom’ with molecule RFM: replace ‘atom’ with
‘formula’
RAM = Σ( mass of isotope x relative abundance)
Σ(relative abundance)
Mass spectrometry
It is assumed that all the ions in a mass spectrum have a single positive charge
Y axis; Relative Abundance Horizontal axis; mass/ mass to charge ratio/ m/z
Diatomic elements e.g. chlorine have 5 peaks
Molecular ion peak: Last major peak/ RMM
Base peak: Peak with the highest relative abundance
A molecular ion is an ion formed from the removal of an electron from a molecule.
Electronic Configuration
Orbital: a region within an atom that can hold up to two electrons with opposite spin
S subshell: one ‘s’ orbital
P subshell: three ‘p’ orbitals D subshell: five ‘d’ orbitals
Type Energy Level Number of this Maximum Shape
type of orbital in number of
a sub shell electrons
s 1 1 2 Spherical
p 2 3 4 Dumbbell
d 3 5 10 Not required
f 4 7 14 Not required
Subshells fill in the following order: 1s,2s,2p,3s,3p,4s,3d,4p
But should be written as 3p, 3d, 4s, 4p/ Electrons are lost as: 4p, 4s, 3d, 3p, 3s, 2s, 1s
