Electronegativity and bonding
Electronegativity
- Electronegativity is an atom's power to attract the electrons in a bond towards itself.
- It follows a clear trend across the Periodic Table.
- The difference between two atoms tells you the bond type.
Practice
Electronegativity is:
Electronegativity measures how strongly an atom pulls the shared bonding electrons towards it.
What sets it, and the trend
- Three factors: nuclear charge (more protons → stronger pull), atomic radius (closer → stronger), shielding (more inner electrons → weaker).
- So it rises across a period and falls down a group.
- Fluorine is the most electronegative element.
Practice
Electronegativity:
More nuclear charge and smaller radius across a period raise it; more shells down a group lower it. F is the highest.
Practice
Which change increases an atom's electronegativity?
More protons (nuclear charge) pull the bonding electrons more strongly; radius and shielding lower it.
Predicting the bond type
- A large electronegativity difference → an ionic bond.
- A small difference → a covalent bond.
- (We compare Pauling electronegativity values.)
Practice
A large electronegativity difference between two atoms gives:
A big difference means electrons are transferred (ionic); a small difference means they are shared (covalent).
You've got it
Key idea
- electronegativity = power to attract bonding electrons
- set by nuclear charge, radius, shielding; rises across, falls down; F is highest
- large difference → ionic; small → covalent