1 Atomic structure
1.1 Particles in the atom and atomic radius
1.2 Isotopes
1.3 Electrons, energy levels and atomic orbitals
1.4 Ionisation energy
Particles in the atom
and atomic radius
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Isotopes
Electrons, energy levels
and atomic orbitals
charge distribution – positive in the middle and negative surrounding this region
Mass distribution: concentrated within centre
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
1. Atomic (proton) number is the number of protons in the nucleus of an atom.
2. Mass (nucleon) number is the total number of protons and neutrons in the nucleus of an atom.
3. Isotopes: are atoms of the same element with the same proton number but different number of
neutrons
• Isotopes have similar chemical properties since they have same number of protons and electrons
(so chemical interactions are similar)
• Isotopes have different physical properties since they have different number of neutrons,
causing them to have different masses and therefore different physical interactions(differ in
atomic weight, density, atomic volume, melting and boiling point)
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
=2n2
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Boron:
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Special electron configuration:
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Shapes of orbital(s & p):
Electrons, energy levels
and atomic orbitals
Ionisation energy
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
• Free radical is an atom, molecule, or ion that has at least one unpaired valence electron.
• Free radical is very unstable, thus very reactive.
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Ionisation energy
Ionization energy: the amount of energy required to remove an electron from an isolated atom or molecule.
Particles in the atom
and atomic radius
Electrons, energy levels
and atomic orbitals
Isotopes
Ionisation energy
Three factors that influence ionisation energies:
The size of the nuclear charge
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number of protons increases
nuclear charge more positive
attractive force between the
nucleus and the electrons
increases
more energy is needed to
overcome these attractive
forces if an electron is to be
removed.
In general, ionisation energy
increases as the proton
number increases.
Distance of outer electrons from
the nucleus
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The force of attraction between
positive and negative charges
decreases rapidly as the
distance between them
increases.
electrons in shells further away
from the nucleus are less
attracted to the nucleus than
those closer to the nucleus.
The further the outer electron
shell is from the nucleus, the
lower the ionisation energy.
Shielding effect of inner electrons
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electrons repel each other.
Electrons in full inner shells repel
electrons in outer shells.
Full inner shells of electrons prevent
the full nuclear charge being felt by
the outer electrons. This is called
shielding.
The greater the shielding of outer
electrons by the inner electron
shells, the lower the attractive forces
between the nucleus and the outer
electrons.
The ionisation energy is lower as the
number of full electron shells
between the outer electrons and the
nucleus increases.
Spin-pair repulsion
•
Electrons in the same
atomic orbital in a
subshell repel each other
more than electrons in
different atomic orbitals
which makes it easier to
remove an electron
(which is why the first
ionization energy is always
the lowest)
Particles in the atom
and atomic radius
Isotopes
Electrons, energy levels
and atomic orbitals
Interpreting successive ionisation energies
Na
Ionisation energy