Physical - Electronegativity Flashcards
Electronegativity
= the power of an atom to attract a pair of electrons in a covalent bond
Two elements that have similar electronegativity
will form a covalent
bond
Two elements that have very different electronegativity
will form an ionic bond.
One atom attracts the pair of electrons so much that they gain the
electrons to form a negative ion.
* The other atom has lost electrons and forms a positive ion
Are metals or non metals more electronegative
non
metals are more
electronegative
than metals
There are three factors affecting electronegativity:
-Nuclear charge
* Shielding
* Atomic radius
Shielding outweighs all
Nuclear charge
The more protons the element has, the greater the nuclear charge, the
stronger the attraction between the nucleus and the bonding pair of
electrons.
Shielding
The nucleus attracts the electrons however electrons repel each other.
This means full electron shells shield the
bonding pair of electrons from the attraction of nucleus.
The more electron shells,
the greater the
shielding effect. This means there is a weaker
attraction between the nucleus and the pair of
electrons in the covalent bond i.e. less
electronegative
Atomic radius
The further away the shared pair of electrons are from the nucleus the more weakly they are attracted
to the nucleus and therefore less electronegative
What factors might affect atomic radius?
*
Nuclear charge – the higher the nuclear charge the stronger the attraction between
nucleus and outer shell electrons therefore they are held closer
* Shielding – the more shielding there is the weaker the attraction between the nucleus
and outer shell electrons therefore they are held further away
Explain why atomic radius decreases across a period
- Outer electrons are in same
shell - There is the same amount of
shielding - More protons in nucleus
- So stronger attraction
between nucleus and outer
shell electrons - So outer shell electrons pulled
closer to nucleus - Atomic radius decreases
The atomic radius increases down a group.
- Outer electrons are in a shell
further away from the nucleus - More shielding
- So weaker attraction between
nucleus and outer shell
electrons - The outershell electrons move
further away from the nucleus - Atomic radius increase
Electronegativity increases
across a period
- Atomic radius decreases
- Nuclear charge increases
- Same shielding
- ∴ Greater attraction between
nucleus and bonding pair of
electro
Electronegativity decreases
down the group
*
Atomic radius increases
* Nuclear charge increase
* More shielding
* ∴ Less attraction between nucleus
and bonding pair of electrons