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Periodicity (Periodic Trends (Metallic character (Trend in metallic and…

- - - - Trends
        
        Ionisation energy decreases down a group
        
        As the number of occupied energy levels increases, the valence electrons are further form the nucleus which result in a weaker electrostatic attraction.
        
        Increased electron shielding by the inner electrons reduces the electrostatic attraction between nucleus and valence electrons
        
        Ionisation energy increases across a period (L to R)
        
        As nuclear charge increases, and electrons are removed from the same main energy level, the electrostatic attraction between the nucleus and valence electrons increases
        
        Atomic radius decreases across a period
      - Exception
        
        Half-filled orbitals
        
        EX: N & O
        N has the electron configuration 1s2 2s2 3p3
        O has the electron configuration 1s2 2s2 2p4
        
        For Oxygen, the electron removed form a doubly occupied p orbital. An electron in a doubly occupied orbital is repelled by the other electron and requires less energy to remove than an electron in a half-filled orbital.
        
        Different orbitals
        
        EX: Be & B
        Be has the electron configuration 1s2 2s2
        B has the electron configuration 1s2 2s2 2p1
        
        Electrons in p orbitals are of higher energy and further form the nucleus than electrons in s orbitals, therefore they require less energy to remove.
  - - - Cations have less occupied energy levels than their parent atoms.
        Cations have more protons than electrons which result in an increased attraction between the nucleus ad the valence electrons.
        The Valence electrons are held more tightly - smaller ionic radius.
    - - Anions have more occupied energy levels than their parent atoms.
        Anions have less protons than electrons which result in an decreased attraction between the nucleus ad the valence electrons.
        The Valence electrons are held less tightly - larger ionic radius.
  - - - Nuclear charge increase across a period, electrons are added to the same main energy level. Therefore, the electrons are pulled closer to the nucleus - ATOMIC RADIUS decreases across a period
    - - The atomic radius increases down a group as the # of occupied energy levels increases
  - - - En is measured on a relative scale called the Pauling scale.
    - - The increase in nuclear charge
      - The decrease in atomic radii
    - - The increase in atomic radii
      - Nuclear charge increased however the effect is shielded by the core electrons
  - - - X(g) + e- ---> X-(g) Negative value (Exothermic)
    - - X-(g) + e- ---> X2-(g) Positive value (Endothermic
    - - In general, non-metal elements tend to have more exothermic electrons affinity values than metallic elements.
      - Electron affinity decreases down a group
        
        Although the effective nuclear charge increased down a group, it is offset by increased electron shielding
        
        The increased atomic radii --> greater electro shielding, the less energy is released when an electron is added.
        
        The greater the distance between the nucleus and the outer energy level, the weaker the electrostatic attraction and less energy is released when an electron is added to the atom.
      - Electron affinity increase across a period
        
        The increased effective nuclear charge
        
        The increased atomic radii
- - - - Good conductor of heat and electricity
        
        Malleable
        
        Ductile
        
        Have lustre
        
        Tend to be oxidised (lose electron)
    - - Poor conductor of heat and electricity
        
        Tend to be reduced (gain electrons in chemical reaction)
    - - Have both metal and non-metal properties