Why did it require two sodium atoms to complete the na2o formula unit? na has 2 charge and o has -1 charge. na has 1 charge and o has -2 charge. na has -2 charge and o has 1 charge.
The correct Answer and Explanation is:
The correct answer is: Na has a 1+ charge and O has a 2- charge.
Explanation:
To understand why two sodium (Na) atoms are required to complete the formula unit for sodium oxide (Na₂O), it’s important to look at the charges of the atoms involved and the rules of chemical bonding.
- Sodium (Na) belongs to Group 1 of the periodic table, meaning it is an alkali metal. Group 1 elements have a tendency to lose one electron to achieve a stable electron configuration, specifically the electron configuration of a noble gas (which has a full outer shell). When sodium loses one electron, it forms a Na⁺ ion with a 1+ charge.
- Oxygen (O), on the other hand, belongs to Group 16 of the periodic table. Oxygen needs two additional electrons to complete its outer shell and reach a stable electron configuration like a noble gas. When oxygen gains two electrons, it forms an O²⁻ ion with a 2- charge.
For a compound to be stable, the total charge in the formula unit must be neutral. In the case of sodium oxide:
- Each sodium atom has a 1+ charge.
- Each oxygen atom has a 2- charge.
To balance the negative charge of oxygen (O²⁻), you need two sodium atoms (Na⁺), each contributing a 1+ charge. This way, the total positive charge from the two sodium atoms (2 × 1+ = 2+) balances the total negative charge from the oxygen atom (2-).
Thus, the formula unit for sodium oxide is Na₂O because:
- Two Na⁺ ions, each with a 1+ charge, are required to balance one O²⁻ ion with a 2- charge.
This principle follows the rule of charge neutrality in ionic compounds, which ensures that the overall charge is zero. Therefore, the formula Na₂O reflects this balance, and the compound is electrically neutral.