Topic 3: Periodicity

3.1 Periodic Table

Groups in the periodic table

  • Metals

    • Good thermal/electric conductors

    • Malleable

    • Ductile

    • Lustre

  • Non-Metals

    • Poor thermal/electric conductor

    • Usually gain electrons

  • Metaloids

    • Both metallic and non-metallic properties

    • Semi-conductors

3.2 Periodic Trends

Atomic Radius 

  • Bonding/covalent atomic radius: Half the distance between the nuclei of two bonding atoms of the same species in a covalent bond.

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

Ionic Radius

  • Cations are smaller than the atom itself

  • 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

  • Definition: minimum energy needed to remove one electron from a neutral gaseous atom in its gaseous state. 

  • General reaction:

Electron affinity

  • Definition: energy required to detach one electron from singly charged negative ion in the gas phase.

  • General reaction:

Electronegativity

  • 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

  • Definition: minimum energy needed to remove one electron from a neutral gaseous atom in its gaseous state. 

Halogens

  • 7 valence electrons, therefore tends to gain one electron

  • Are usually diatomic (     )

  • More electronegative halogens react in ionic reactions.

Alkali metals

  • Have only one valence electron     ,therefore tends to lose the electron 

  • The reaction is more vigorous down the group.

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