Determine the chemical formula for the ionic compound that forms between sodium and sulfur.
The correct answer and explanation is :
The ionic compound that forms between sodium (Na) and sulfur (S) is sodium sulfide, and its chemical formula is Na₂S.
Explanation:
To determine the formula of an ionic compound, we need to understand how the atoms involved interact. Sodium (Na) and sulfur (S) combine to form an ionic bond based on their respective charges.
- Sodium (Na): Sodium is an alkali metal found in Group 1 of the periodic table. It has a single electron in its outer shell (valence electron), which it tends to lose in order to achieve a stable electron configuration similar to the nearest noble gas, neon. When sodium loses this electron, it becomes a positively charged ion (cation) with a charge of +1 (Na⁺).
- Sulfur (S): Sulfur is a non-metal found in Group 16 of the periodic table. It has six valence electrons and needs two more electrons to complete its outer shell, reaching the stable electron configuration of the nearest noble gas, argon. By gaining two electrons, sulfur becomes a negatively charged ion (anion) with a charge of -2 (S²⁻).
Ionic Bond Formation:
When sodium and sulfur come together, sodium atoms lose electrons to become Na⁺ cations, while sulfur gains electrons to become an S²⁻ anion. Since the charges must balance in an ionic compound, we need two sodium ions (each with a +1 charge) to balance one sulfur ion (with a -2 charge). Therefore, the formula for the compound is Na₂S, meaning two sodium ions combine with one sulfur ion to form sodium sulfide.
Key Points:
- Sodium (Na) forms Na⁺ ions by losing one electron.
- Sulfur (S) forms S²⁻ ions by gaining two electrons.
- To balance the charges, two Na⁺ ions are needed for every S²⁻ ion.
- The chemical formula of the compound is Na₂S, indicating two sodium ions for every sulfur ion.
Thus, the ionic compound between sodium and sulfur is Na₂S.