The exact chemical formula for gold (III) nitrate is Au(NO₃)₃.
This formula represents a compound formed between gold, a precious metal, and the nitrate polyatomic ion. Understanding its components and how they interact chemically is key to deriving its correct representation.
Understanding the Components
To determine the formula for gold (III) nitrate, we first need to identify its constituent ions and their respective charges (valencies).
- Gold (Au): The Roman numeral "III" in parentheses indicates the oxidation state of gold in this compound. Therefore, gold exists as a cation with a +3 charge, written as Au³⁺. Gold is a transition metal and can exhibit various oxidation states, but in this specific compound, its charge is explicitly stated as +3.
- Nitrate (NO₃): Nitrate is a polyatomic anion. It consists of one nitrogen atom and three oxygen atoms, carrying a net charge of -1. Its formula is NO₃⁻.
These components are essential building blocks for ionic compounds like gold (III) nitrate.
| Ion Name | Symbol | Charge |
|---|---|---|
| Gold (III) | Au³⁺ | +3 |
| Nitrate | NO₃⁻ | -1 |
Deriving the Chemical Formula
Chemical formulas for ionic compounds are determined by balancing the total positive and negative charges to achieve electrical neutrality. This is often done using the "criss-cross" method or by finding the least common multiple of the charges.
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Identify the charges:
- Gold (Au): +3
- Nitrate (NO₃): -1
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Balance the charges: To neutralize the +3 charge of one gold ion, we need three nitrate ions, as each nitrate ion carries a -1 charge (3 x -1 = -3).
- Au³⁺ + 3(NO₃⁻) → Au(NO₃)₃
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Write the formula: The cation (gold) is written first, followed by the anion (nitrate). Parentheses are used around the polyatomic ion (nitrate) when more than one is needed, and the subscript outside the parentheses indicates the number of those ions.
Therefore, combining one gold (III) ion with three nitrate ions yields the formula Au(NO₃)₃.
Properties and Related Concepts
Gold (III) nitrate is an inorganic salt. Like many metal nitrates, it is typically soluble in water. Compounds involving gold, especially in higher oxidation states, can have distinct chemical properties and may be used in various applications, including:
- Catalysis: Gold compounds can act as catalysts in various chemical reactions.
- Electroplating: Used in some gold plating processes.
- Research: Employed in chemical research, particularly in the study of gold chemistry and materials science.
Understanding the systematic nomenclature of chemical compounds, including Roman numerals for transition metal oxidation states and the names of polyatomic ions, is fundamental to correctly writing chemical formulas. For further study on chemical nomenclature, a reliable resource like the International Union of Pure and Applied Chemistry (IUPAC) provides comprehensive guidelines.
