Periodicity

• How is the modern periodic table arranged?

  The elements are arranged in order of increasing atomic numbers.

  -> this arrangement reveals patterns in the properties of elements, allowing chemists to make predictions about their behaviour.
• Why do elements in the same group exhibit similar properties?

  Elements in the same group have similar electron configurations in their outer shell; so they exhibit similar physical and chemical properties.
• Which element in period 3 has the highest melting point? Why?

  Silicon (Si)

  • Giant covalent lattice structure.

  • Each atom is covalently bonded to 4 other atoms in a tetrahedral arrangement.

  • This forms very strong bonds linking all the atoms together in a 3D lattice.

  • A huge amount of energy is required to break these covalent bonds, resulting in a very high melting and boiling point.