Chemistry

• Percentage of nitrogen in atmosphere

  78 %
• As atomic mass increases, melting point, boiling point, and density increase due to stronger forces of attraction
• Reactivity of non-metals decreases as atomic mass increases

  
  

  More shielding - more shells

  Outer shell further away from the nucleus

  Weaker force of attraction between positive nucleus and negative electrons

  Harder to gain electrons to the outer shell
• Reactivity of metals increases as atomic mass increases

  
  

  Easier to lose electrons as they are further away from the positive nucleus - more shielding due to more shells