The Octet Rule
The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable configuration with eight electrons in their outermost energy level (valence shell). This configuration resembles that of the noble gases, which are chemically unreactive due to their full outer shells.
Sodium's Electron Configuration
* Sodium (Na) has an atomic number of 11, meaning it has 11 protons and 11 electrons.
* Its electron configuration is 2, 8, 1. This means it has one electron in its outermost shell.
Formation of the Sodium Ion
To achieve a stable octet, sodium needs to get rid of its lone valence electron. This is accomplished by:
1. Losing an Electron: Sodium loses its single valence electron. This loss leaves it with 10 electrons, and the configuration of the previous noble gas, neon (2, 8).
2. Positive Charge: Losing a negatively charged electron leaves the sodium atom with one more proton than electrons. This results in a net positive charge of +1.
3. Sodium Ion: The resulting positively charged sodium atom is now a sodium ion (Na+).
Summary
Sodium forms a positive ion (Na+) by losing its single valence electron to achieve a stable octet configuration like the noble gas neon. This process aligns with the octet rule, which explains how atoms strive for stability by gaining, losing, or sharing electrons to attain a full outer shell.
