Question #f2f9a

1 Answer
Jul 21, 2017

A cation with charge #1+# (most all of the time)


The metals in group 1 (#"Li"#, #"Na"#, #"K"#, #"Rb"#, #"Cs"#, #"Fr"#) are generally very reactive and readily give up their lone outer-shell electron.

Hydrogen, as well, can give up its single electron to form a cation with an ionic charge #1+#.

As of yet, we haven't observed any of these elements to give up more than one electron, because of their very high second ionization energies (i.e. it takes a LOT of energy to remove an electron after it removes its single valence electron).

As a matter of fact, every group 1 element (aside from lithium and francium) has also been observed to accept an electron to form a #1-# anion. Hydrogen, being a nonmetal, does this much more than any of the other alkali metals (it forms hydrides).

Compounds where the alkali metal is the anion of a compound are called alkalides, and were first discovered in the 1970s. These are still interesting to chemists today, because of their unusual characteristics; before, people believed the group 1 metals could only form cations.

All in all, these "alkalides" are of little importance to many, so just know that the alkali metals generally form #1+# cations.