Ionization Energy and Factors Affecting It

Study Notes

Definition

Ionization energy is the energy required to remove an electron from a neutral atom or molecule in its ground state, resulting in the formation of a cation.

Factors Affecting Ionization Energy

Atomic size: Ionization energy decreases as atomic size increases.
Nuclear charge: Ionization energy increases as nuclear charge increases.
Shielding: Inner electrons shield outer electrons from the nuclear charge, decreasing ionization energy.
Electron configuration: Ionization energy is higher for atoms with full or half-full outer energy levels.

Trends in the Periodic Table

Across a period: Ionization energy increases from left to right due to increasing nuclear charge.
Down a group: Ionization energy decreases due to increasing atomic size.

Types of Ionization Energy

First ionization energy: Energy required to remove one electron from an atom.
Successive ionization energies: Energies required to remove subsequent electrons.

Importance of Ionization Energy

Chemical reactivity: Ionization energy influences an element's ability to form compounds.
Physical properties: Ionization energy affects an element's physical properties, such as electronegativity and electron affinity.

Ionization Energy Definition

Ionization energy is the energy required to remove an electron from a neutral atom or molecule in its ground state, forming a cation.

Factors Affecting Ionization Energy

Atomic size: Ionization energy decreases as atomic size increases because the outer electron is farther from the nucleus.
Nuclear charge: Ionization energy increases as nuclear charge increases because the attraction between the nucleus and outer electron strengthens.
Shielding: Inner electrons shield outer electrons from the nuclear charge, decreasing ionization energy as the outer electron is not strongly attracted to the nucleus.
Electron configuration: Ionization energy is higher for atoms with full or half-full outer energy levels due to the stability of these configurations.

Periodic Trends

Across a period: Ionization energy increases from left to right due to increasing nuclear charge, making it harder to remove an electron.
Down a group: Ionization energy decreases down a group due to increasing atomic size, making it easier to remove an electron.

Types of Ionization Energy

First ionization energy: Energy required to remove one electron from an atom.
Successive ionization energies: Energies required to remove subsequent electrons, which are always higher than the first ionization energy.

Importance of Ionization Energy

Chemical reactivity: Ionization energy influences an element's ability to form compounds, with higher ionization energy indicating lower reactivity.
Physical properties: Ionization energy affects an element's physical properties, such as electronegativity and electron affinity, which are related to the ease of electron removal.