Here's why:

* Electron Configuration: Sodium has an electron configuration of 2, 8, 1. This means it has one electron in its outermost shell (valence shell).

* Octet Rule: Elements strive to achieve a stable configuration of eight electrons in their valence shell (octet rule).

* Ionic Bonding: Sodium readily loses its single valence electron to form a positively charged ion (Na+). This loss allows it to achieve a stable electron configuration similar to the noble gas neon (Ne).

Therefore, sodium readily lends its one valence electron to form ionic bonds with other elements.