Electronic configuration

• How many electrons can an s sub shell hold?

  2
• How many electrons can a p subshell hold?

  6
• How many electrons can a d sub shell hold?

  10
• What is the trend in ionisation energy across period 2?

  Increasing
• What is ionisation energy?

  The energy required to remove an electron from a mole of gaseous atoms to produce a mole of gaseous positive ions
• What is the reason for the trend in IE of period 2?


  Increasing nuclear charge.

  same shielding

  atomic radius decreases

  therefore a stronger attraction of the electron being removed and the nucleus, requiring more energy.
• The change of IE in beryllium to boron?

  In Boron, the outer electron goes into the 2p subshell which is at a higher energy level than the 2s subshell. This means more energy is required to remove the outer electron in B compared to Be
• What is the change in IE of nitrogen to oxygen?

  In oxygen, in the 2p subshell the electrons in one orbital are paired which causes repulsion so it requires less energy to remove the outer electron.