Across a period covalent radius
Decreases
Electron shells stays the same
Nuclear charge increases- more strongly attracted to nucleus
Down a group the covalent radius
Increases
Nuclear charge increases
More electron shells
Number of shells outweighs nuclear charge- each extra layer shields the outer electrons from the nucleus so the outer electrons are less strongly attracted to the nucleus
Down a group the electronegativity
Decreases
No. of filled electron shells increases- screens the bonded electrons from the nuclear charge so electrons are less strongly attracted to the atom
Across a period electronegativity
Increases
Nuclear charge increases
Electronegativity
A measure of attraction for electrons in a covalent bond
Higher electronegativity= stronger attraction for electrons