Ionization Energy

What is ionization energy?

The energy required to remove an electron from an atom.

What is the trend for ionization energy across a period?

Ionization energy increases from left to right across a period due to an increasing number of protons and effective nuclear charge.

Why does ionization energy increase up a group?

Moving up a group reduces the number of electron shells, which decreases the shielding effect and strengthens the attraction between the nucleus and the outermost electron, making it harder to remove.

Why does argon have a high ionization energy?

is a noble gas with a completely filled valence shell, making it highly stable and requiring more energy to remove an electron.

What happens to ionization energy when removing successive electrons?

The ionization energy increases with each successive electron removed, as the atom becomes more positively charged and the remaining electrons are held more tightly.

Why is the second ionization energy of sodium much higher than the first?

After the first electron is removed, sodium achieves a stable electron configuration. Removing another electron disrupts this stability and requires significantly more energy.

Why do alkaline earth metals (Group 2) have higher ionization energy than Group 13 elements in the same period?

Alkaline earth metals have filled orbitals, which makes them more stable and harder to ionize compared to Group 13 elements.

Why do Group 15 elements have higher ionization energy than Group 16 elements in the same period?

have half-filled orbitals, which provide greater stability and result in higher ionization energy compared to Group 16 elements.

What are the two exceptions to the general ionization energy trend?

• Alkaline earth metals have higher ionization energy than Group 13 elements due to filled orbitals.

• Group 15 elements have higher ionization energy than Group 16 elements due to half-filled orbitals.