⚡ IONISATION ENERGY
PAGE 1 OF 5, STEALING ELECTRONS
THE TUG OF WAR
WHAT IS IONISATION ENERGY?
First ionisation energy is the energy needed to remove one mole of electrons from one mole of gaseous atoms, forming one mole of gaseous 1+ ions. It measures how tightly the outer electron is held. A high value means the electron is hard to steal.
⚡ FIRST IE
X(g) → X⁺(g) + e⁻. Energy input is required to overcome attraction to the nucleus.
STEAL!
TIGHT HOLD
🔒 High IE means hard to remove
😴 Noble gases have high IE
📍 Outer electron held firmly
😴 Noble gases have high IE
📍 Outer electron held firmly
LOOSE HOLD
🔓 Low IE means easier to remove
⚡ Alkali metals have low IE
➕ Easy to form cations
⚡ Alkali metals have low IE
➕ Easy to form cations