JAMB - Chemistry (2004 - No. 8)
An electron can be added to a halogen atom to form a halide ion with
2 valence electrons
3 valence electrons
7 valence electrons
8 valence electrons
Explication
When an electron is added to a halogen atom, it will have eight valence electrons. Halogens have seven valence electrons in their outermost shell. When an electron is added to a halogen atom, it fills its outermost shell, resulting in a full valence shell of 8 electrons.