Ionisation Energy

• What is the definition of 1st ionisation energy?

  The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of ions.
• What is the equation for first ionisation energy?

  X(g) -> X(g)+ + e-
• What is the definition of nuclear charge?

  The number of protons in the nucleus
• What is the definition of atomic radius?

  The distance between the outer electron and the nucleus
• What is the definition of electron shielding?

  How many shells are between the outer electron and the nucleus
• Does nuclear charge increase or decrease across periods and down groups?

  Increases across periods, increases down groups
• Does atomic radius increase or decrease across periods and down groups?

  Radius decreases across periods and increases down groups
• Does ionisation energy increase or decrease across periods?

  Increase
• Which groups break the trend in ionisation energy?

  Group 3 and Group 6
• What is the group 3 explanation for breaking the trend?

  The _p sub shell of X is a higher energy level than the _s sub shell of Y
• What is the group 6 explanation for breaking the trend?

  There are paired electrons in the _p sub shell of X which repel and lower ionisation energy
• Is ionisation endothermic or exothermic and why?

  Endothermic as it requires energy to remove the electrons