Explaining trends

• As you go down groups in the periodic table atoms get larger as they are gaining a shell for every row
• As a result, larger metal atoms lose electrons more easily. See fig. 1

  
• Larger non-metal atoms gain electrons less easily. See fig. 2

  
• Electrons are negatively charged and protons in the nucleus are positively charged
• There is an attraction between them, and this is called electrostatic force of attraction
• There is a weaker force of attraction between the nucleus and outer shell electron/s if the atom is larger. This is because there are more shells and this provides more ‘shielding’ between the nucleus and outer electron/s
• For metals, these electrons are more easily lost and as a result, the metal is more reactive
• For large non-metal atoms, the incoming electron is also further away from the nucleus and is less easily gained by the atom due to more shells = more shielding. As a result, the atom is less reactive.