Calcium hydroxide, chemically represented as \( \text{Ca(OH)}_2 \), consists of calcium ions (\( \text{Ca}^{2+} \)) and hydroxide ions (\( \text{OH}^- \)). The negative ion in calcium hydroxide is the hydroxide ion (\( \text{OH}^- \)). Each molecule of calcium hydroxide contains two hydroxide ions, which contribute to its alkaline properties.
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