Why are the second ionisation energies of calcium and strontium greater than their first ionisation energies?

  • -2 votes


Posted Mon 5th November, 2012 @ 20:04 by anonymous

2 Answers

  • 3 votes

Basically when you remove one electron, u need a certain amount of energy, or the first ionisation energy. This is a certain amount of energy depending on the element, and when you have taken the first electron, you leave a positive ion behind, which makes a stronger attraction on the remaining electrons. Imagine u had cake, someone steals a piece, so you decide to protect the other pieces more, LOL. This means that as you get to the second ionisation energy or removing a second electron, it requires more energy to remove, and the third IE requires more than the second, and so on.

Factors affecting the IE are:

  • Distance from nucleus
  • Amount of shielding
  • Number of electrons in outer shell (Ithink!)

Hope thsi helps :)

Answered Thu 8th November, 2012 @ 19:08 by Nearly Einstein
  • 1 vote

Once you have removed the first electron you are left with a positive ion. Trying to remove a negative electron from a positive ion is going to be more difficult than removing it from an atom as there is the same positive charge but less electrons so the positive charge has a greater effect on the remaining electrons.

This website explains it well: http://www.chemguide.co.uk/atoms/properties/moreies.html#top

Answered Thu 8th November, 2012 @ 17:49 by Sophie