Electron Shells and Ions.
Groups 1 & 2 and 6 & 7 are the Most Likely to Form Ions.
1) Remember, atoms that have lost or gained an electron (or electrons) are ions.
2) The elements that most readily form ions are those in Groups 1, 2, 6 and 7.
3) Group 1 and 2 elements are metals and they lose electrons to form +ve ions or cations.
4) Group 6 and 7 elements are non-metals. They gain electrons to form -ve ions or anions.
5) You need to know the easy ones: