Elements in Groups 1 and 2 of the periodic table, known as the alkali metals and alkaline earth metals, respectively, are likely to lose electrons from their valence shells.
Group 1 elements (alkali metals) have one valence electron, while Group 2 elements (alkaline earth metals) have two valence electrons. These elements have relatively low ionization energies, which means it requires less energy for them to lose their valence electrons and form positive ions.
When these elements lose electrons, they achieve a stable electron configuration similar to that of a noble gas. For example, Group 1 elements like sodium (Na) can lose their single valence electron to form a sodium ion (Na+), which has the same electron configuration as neon (Ne). Similarly, Group 2 elements like magnesium (Mg) can lose their two valence electrons to form a magnesium ion (Mg2+), attaining the electron configuration of helium (He).
By losing valence electrons, these elements can achieve a more stable and lower energy state, making them more likely to undergo electron loss and form positive ions in chemical reactions.