What is the chemical name for the compound with the formula Na2S? a. sodium fluoride b. magnesium sulfide c. lithium oxide d. sodium sulfide
The correct answer and explanation is:
The correct answer is d. sodium sulfide.
Explanation:
The chemical formula Na₂S consists of two sodium (Na) atoms and one sulfur (S) atom. Sodium is an alkali metal found in Group 1 of the periodic table, and it typically forms ions with a +1 charge (Na⁺). Sulfur, a nonmetal found in Group 16, commonly forms ions with a -2 charge (S²⁻).
To balance the charges in the compound, two sodium ions (each +1) combine with one sulfide ion (with a -2 charge), giving the neutral compound Na₂S.
Breaking down the answer choices:
a. Sodium fluoride (NaF) contains sodium and fluoride ions, not sulfide. Its formula is NaF, with one sodium ion and one fluoride ion.
b. Magnesium sulfide (MgS) contains magnesium (Mg²⁺) and sulfide (S²⁻) ions, but magnesium is a different metal and the formula is MgS, not Na₂S.
c. Lithium oxide (Li₂O) consists of lithium (Li⁺) and oxide (O²⁻) ions, and the formula is Li₂O, not Na₂S.
d. Sodium sulfide (Na₂S) contains sodium and sulfide ions in the correct ratio to balance charges.
Sodium sulfide is an ionic compound formed by the transfer of electrons from sodium atoms to the sulfur atom. The sodium atoms lose one electron each to become positively charged sodium ions, while sulfur gains two electrons to become a negatively charged sulfide ion. This transfer leads to an electrostatic attraction between the oppositely charged ions, creating a stable ionic bond.
Sodium sulfide is commonly used in various industrial applications, such as in the manufacture of paper, textiles, and dyes, as well as in water treatment. It appears as a yellowish solid and is soluble in water, where it dissociates into sodium and sulfide ions. Understanding the formula and naming of ionic compounds like Na₂S is important in chemistry for identifying the components and properties of substances.