Explain how electronegativity varies within a group and across a period.
Electronegativity decreases from top to bottom within a group. Electronegativity increase from left to right across a period.
500
Explain how ions form. Provide at least one example.
Ions form when an atom gains or loses electron(s). Electrons can only be lost from the outer shell. The amount that will be gained or lost depends on how many it will take to reach the electron configuration of a noble gas.