Answer: An atom that has gained an electron.
Explanation:
The number of protons in an atom cannot change except for some exceptional circumstances.
Cations (or metal ions) are formed when atoms lose electrons, as they want to form a complete outer electron shell to become as stable as possible.
For example, potassium is a 1+ ion, because it has one electron in its outer shell (and in group one). Therefore, to become more stable that electron is lost to become an ion or cation. As one electron is lost, the potassium cation charge is 1+ as the charge of an electron is 1-.
Yes since for atoms to be of the same element , they must have the same number of protons inside their nucleus . This means that 1- they will all have the same nucleon number ( mass number ) and that 2-they will all have the same number of electrons in their outermost shell which determines the chemical properties of the atom.
The answer to your question is true