Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. It increases across a period as the proton number and effective nuclear charge increases, making the nucleus more able to attract electrons. However, electronegativity decreases down a group as the energy level and shielding effect increases, weakening the attraction between the nucleus and valence electrons. Electron affinity is the energy change when an electron is added to a neutral atom to form a negative ion. It is measured as the electron attachment energy or electronegativity.

1. Electro negativity
and
Electron affinity
PREPARED BY
AMRUTHA TK

2. Electronegativity
• Electronegativity is a measure of an
atom’s attraction for another atom’s
electrons.
Electronegativity increases
Electronegativity
increases

3. Trend in electronegativity across a period and down
the group:
Increases across a period
• Proton number increases
• Effective nuclear charge increases
• Stronger attraction between nucleus and
valence electron
• Atomic radius decreases
• Greater ability to attract the bonding electrons to
itself
• Thus, electronegativity increases
Electronegativity

4. Electronegativity
Decreases down a group
• Energy level increases
• Shielding effect increases
• Weaker attraction between nucleus and
valence electron
• Atomic radius increases
• Weaker ability to attract the bonding
electrons to itself.
• Thus, the electronegativity decreases

5. FACTOR AFFECTING
ELECTRONEGATIVITY

6. ELECTRONEGATIVITY SCALE

7. ELECTRON AFFINITY
• ElectronAffinity: energy that occurs when an electron is added to a
neutral atom in the gaseous state to form a negative ion.
• X(g) + e- X-(g)
• E = electron attachment energy
• Electron affinity =-E (electron attachment energy or
electrone gain enthalpy)
• SecondElectronAffinity: Second electron affinity of n element M(g) is
defined as the amount of energy required to add one more
electron to its mononegative anion, to form dinegative anion.
• The addition of second electron to uni- negative ion is an
endothermic process.