Topic 3: Periodicity
3.1 Periodic Table
Groups in the periodic table
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Metals
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Good thermal/electric conductors
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Malleable
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Ductile
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Lustre
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Non-Metals
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Poor thermal/electric conductor
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Usually gain electrons
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Metaloids
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Both metallic and non-metallic properties
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Semi-conductors
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3.2 Periodic Trends
Atomic Radius
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Bonding/covalent atomic radius: Half the distance between the nuclei of two bonding atoms of the same species in a covalent bond.

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Non-Bonding atomic/van der Waal's radius: radius of two non bonding frozen argon atoms

Ionic Radius
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Cations are smaller than the atom itself
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Anions are bigger than the atom itself
Note: you should be able to explain why each ion has a bigger or smaller radius than the atom.
Ionization Energy
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Definition: minimum energy needed to remove one electron from a neutral gaseous atom in its gaseous state.
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General reaction:


Electron affinity
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Definition: energy required to detach one electron from singly charged negative ion in the gas phase.
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General reaction:


Electronegativity
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Definition: The relative attraction that an atom has for the shared pair of electrons in a covalent bond

Metallic and non-metallic character

Metal and non-metal oxides
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Definition: minimum energy needed to remove one electron from a neutral gaseous atom in its gaseous state.

Halogens
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7 valence electrons, therefore tends to gain one electron
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Are usually diatomic ( )
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More electronegative halogens react in ionic reactions.
Alkali metals
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Have only one valence electron ,therefore tends to lose the electron
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The reaction is more vigorous down the group.

