Ionisation energy

• What is the first ionisation energy?

  Energy needed to remove one mole of electrons
• What does the first ionisation energy produce?

  One mole of gaseous ions with a single positive charge
• What is the equation for the first ionisation energy?

  NXg) → X+(g) + e
• What is the second ionisation energy?

  Energy needed to remove one mole of electrons from singly charged ions
• What does the second ionisation energy produce?

  One mole of gaseous ions with a double positive charge
• What is the equation for the second ionisation energy?

  X(g)+ → X2+(g) + e
• What factors influence ionisation energies?

  Number of shells, shielding, nuclear charge, atomic radius
• How does the number of shells affect ionisation energy?

  More shells increase shielding, making electrons easier to lose
• What is the effect of nuclear charge on ionisation energy?

  More protons increase attraction, raising ionisation energy
• How does atomic radius influence ionisation energy?

  Greater distance from nucleus makes electrons easier to lose
• What happens to ionisation energy down a group?

  Ionisation energy decreases as shielding increases
• Why does ionisation energy increase as more electrons are removed?

  Greater attraction to nucleus as charge on ion increases
• What trend occurs in ionisation energy across a period?

  Ionisation energy increases due to higher nuclear charge
• How does atomic size change across a period?

  Atomic size decreases as nuclear charge increases
• What are the factors influencing ionisation energies?

  • Number of shells
  • Shielding effect
  • Nuclear charge
  • Atomic radius
• What is the trend of ionisation energy down a group and why?

  • Ionisation energy decreases
  • Due to increased shielding and atomic radius
• What is the trend of ionisation energy across a period and why?

  • Ionisation energy increases
  • Due to increased nuclear charge and decreased atomic size