Describe one chemical property of group 1 metals that results from the atoms of each metal having only one valence electron.

Their ability to lose that electron easily. This property is electronegativity. Once that electron is taken away, the atom becomes an ion with a charge of +1. The ion would be much more stable than the atom, because once the electron is lost, the shell underneath will already have 8 electrons that resembles the configuration of a noble gas.