If an element gains an electron, will it form a positive ion or a negative ion?

Negative Ion An atom on gaining an extra electron will acquire one unit of negative charge. An atom has equal number of protons and electrons. The total positive charge of protons balance out the total negative charge of electrons.

What is an atom with an extra electron? - Quora

Ions - Meaning and Examples [in Chemistry] - Teachoo - Concepts

Chemical Bonding Review Worksheet - Chemical Bonding Review

Chemical Bonding Review WS 1 .pdf - Chemical Bonding Review

Ions

Chemical Bonding Review WS 1 .pdf - Chemical Bonding Review

What is an ion?

MarshScience7: The Modern Atomic Model

Ionic Bond Examples