Accepted answer
Answer included
Aluminum nitrate formula
The phrase aluminum nitrate formula refers to the neutral ionic compound formed from the aluminum cation and the nitrate polyatomic anion. The correct formula is obtained by combining ions so the total charge sums to zero.
Final formula: \( \mathrm{Al(NO_3)_3} \)
Charge check: \( \mathrm{Al^{3+}} + 3 \times \mathrm{NO_3^-} \rightarrow \mathrm{Al(NO_3)_3} \) because \( (+3) + 3(-1) = 0 \).
Step-by-step method (charge balancing)
- Write the ions and their charges. Aluminum forms \( \mathrm{Al^{3+}} \). Nitrate is the polyatomic ion \( \mathrm{NO_3^-} \).
- Balance total positive and negative charge. One \( \mathrm{Al^{3+}} \) requires three \( \mathrm{NO_3^-} \) ions to neutralize the \( +3 \) charge.
- Write the formula using parentheses for repeated polyatomic ions. Because nitrate has more than one atom and appears three times, write \( \mathrm{(NO_3)_3} \). The complete neutral compound is \( \mathrm{Al(NO_3)_3} \).
Ion information used
| Species | Type | Ion symbol | Charge | Role in formula writing |
|---|---|---|---|---|
| Aluminum | Cation (metal) | \( \mathrm{Al^{3+}} \) | \( +3 \) | Provides total \( +3 \) charge that must be balanced. |
| Nitrate | Anion (polyatomic) | \( \mathrm{NO_3^-} \) | \( -1 \) | Three nitrates supply total \( -3 \) charge to neutralize aluminum. |
Visualization: matching charges to build a neutral formula
Visualization: matching charges to build a neutral formula
Common mistakes to avoid
- Forgetting parentheses: writing \( \mathrm{Al(NO_3)_3} \) is incorrect notation; repeated polyatomic ions must be grouped as \( \mathrm{(NO_3)_3} \).
- Using the wrong subscripts: the “3” in \( \mathrm{Al(NO_3)_3} \) applies to the entire nitrate group, not only to oxygen.
- Not checking charge neutrality: a valid ionic formula must satisfy total charge \( = 0 \).
Vote on the accepted answer
Upvotes: 0
Downvotes: 0
Score: 0