Ionization Enthalpy
Defines the energy required to remove an electron from an isolated gaseous atom and explores factors affecting it and its periodic variations.
What is Ionization Enthalpy?
The minimum energy required to remove the most loosely bound electron from a neutral gaseous atom in its ground state.
Key points
- Define ionization enthalpy.
- Explain the factors affecting ionization enthalpy.
- Describe the periodic trends of ionization enthalpy across periods and down groups.
- Differentiate between successive ionization enthalpies.
Common exam trap
Confusing ionization enthalpy with electron affinity.
Definitions
- Term
Ionization Enthalpy (ΔiH)
- Meaning
The minimum energy required to remove the most loosely bound electron from a neutral gaseous atom in its ground state.
- Term
First Ionization Enthalpy (ΔiH1)
- Meaning
The energy change for the process M(g) → M+(g) + e-.
- Term
Second Ionization Enthalpy (ΔiH2)
- Meaning
The energy change for the process M+(g) → M2+(g) + e-.
Learning objectives
Define ionization enthalpy.
Explain the factors affecting ionization enthalpy.
Describe the periodic trends of ionization enthalpy across periods and down groups.
Differentiate between successive ionization enthalpies.
Prerequisites
Atomic Structure (protons, neutrons, electrons, electron shells, subshells)
Electronic Configuration
Periodic Table trends (atomic radius, shielding effect)
Common mistakes
Confusing ionization enthalpy with electron affinity.
Forgetting that the atom must be in the gaseous state.
Underestimating the stability of half-filled and fully-filled orbitals.
Assuming a linear trend without considering exceptions.
Keywords
Ionization Energy
IE
Electron Removal
Gaseous Atom
Nuclear Charge
Atomic Radius
Shielding Effect
Electronic Configuration
Periodic Trends
Practice preview
Why does the first ionization enthalpy generally increase across a period in the periodic table?…
easy
Which of the following pairs of elements will have the largest difference in their first ionization enthalpies?…
hard
Which of the following orders of first ionization enthalpies is correct?…
medium