Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself when it is covalently bonded to another atom. Electron gain enthalpy is the energy change when an isolated gaseous atom gains an extra electron to form a negative ion (anion).

Quick Scoop

1. Simple definitions

  • Electronegativity :
    Tendency of an atom in a molecule to attract the shared pair of electrons towards itself.
  • Electron gain enthalpy :
    Energy released or absorbed when a neutral isolated gaseous atom accepts an electron to form an anion.

Think of it like this:

Electron gain enthalpy talks about “how much energy change when I gain an electron alone”,
Electronegativity talks about “how strongly I pull electrons when I am bonded”.

2. How they differ (key points)

  • Type of quantity
    • Electronegativity: Relative, unitless, given on scales like the Pauling scale.
* Electron gain enthalpy: Has units (kJ mol⁻Âč or eV per atom), it is an actual energy change.
  • Situation considered
    • Electronegativity: Atom is in a bond (in a molecule or compound), attracting shared electrons.
* Electron gain enthalpy: Atom is **isolated and gaseous** , directly gaining an extra electron.
  • What they measure
    • Electronegativity: “Pulling power” for shared electrons in a bond.
* Electron gain enthalpy: “Energy effect” when an electron is added to the atom (how favorable that addition is).
  • Sign / nature
    • Electronegativity: Always taken as a positive scale value (e.g., fluorine has highest value).
* Electron gain enthalpy: Can be negative (energy released, favorable) or positive (energy absorbed, unfavorable, e.g., noble gases).
  • Direct vs derived
    • Electronegativity: Derived concept (cannot be measured directly as a single experiment).
* Electron gain enthalpy: Thermodynamic quantity, measurable in principle via energy changes.

3. Neat comparison (for quick revision)

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Feature Electronegativity Electron gain enthalpy
Basic idea Tendency of an atom to attract shared electrons in a bond.Energy change when an isolated gaseous atom gains an electron.
System considered Atom in a molecule/compound.Neutral isolated gaseous atom.
Type of quantity Relative, unitless (Pauling scale, etc.).Thermodynamic quantity with units (kJ mol⁻Âč, eV).
Sign / nature Always expressed as positive scale values.Can be negative (exothermic) or positive (endothermic).
Main focus Pull on bond electrons.Energy effect of adding an electron.

4. One-line exam-style distinction

  • Electronegativity: Tendency of an atom in a molecule to attract a shared pair of electrons towards itself.
  • Electron gain enthalpy: Energy change when an isolated gaseous atom gains an electron to form an anion.

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