Which groups of elements tend to form positive ions?
Group 1A: The Alkali Metals: H, Li, Na, and K
Group 2A: The Alkali Earth Metals: Be, Mg, and Ca
Group 3A: The Boron Family: For the most part, only Al
These atoms all want to get rid of their 'remainder' electrons so they have a full outer shell; like the Noble Gases.
Group 1A only has to loose 1 electron to be in its 'happy' state. (+1 charge)
Group 2A has to loose 2 electrons (+2 charge)
Group 3A has 3 to loose. (+3 charge)
Since a regular atom is naturally neutral (equal number of electrons to protons), loosing electrons (which are negative) off set the atom's 'balance of charge' and make it positive. At this point, the atom is no longer an atom, but an ion.