Bond

Ionic Bond Unit 4: Ionic Compounds

Formation of Ionic Compounds Ionic compounds are composed of cations (metals) and anions (nonmetals). Although they are composed of ions, ionic compounds are electrically neutral. The positive charge equals the negative. The positive charge and the negative charge attract one another. This is how the bond is formed.

Formula Units Chemists represent the composition of substances by writing a chemical formula. A chemical formula shows the kinds and number of atoms in a substance. Examples: Sodium Chloride: NaCl Copper Fluoride: CuF2

Formula Units Ionic compounds exists as collection of negative and positive charge arranged in repeated patterns. The chemical formula for an ionic compound, the formula unit, represents the smallest whole number ratio. Examples: Magnesium Oxide: MgO Magnesium Nitride: Mg3N2

Properties of Ionic Compounds Most ionic compounds are crystalline solids at room temperature Ionic compounds generally have high melting points. Ionic Compounds can conduct electricity when melted or dissolved. This is because ionic compounds break down into their IONS when melted or dissolved in water.

Naming Binary Ionic Compounds To name any binary ionic compound , place the cation first, followed by the anion name. “Binary” just means that the compound has two elements in the formula. The name of Cs2O, is cesium oxide.

Practice! LiF Name: 2. BaO Name: 3. BaCl2 Name: 4. K2O Name: Lithium Flouride Barium Oxide Barium Chloride Potassium Oxide

Drawing Electron Transfers Draw the Lewis dot structure for each element: Try Mg and Cl: 2. Use arrows to show how electrons move. Add more ions if needed.

3. Write the formula by writing the number of ions used next to the symbol for each element. Formula: ___________________

2 Ways to Write Ionic Compounds (Without drawing dot structures) Write the element symbols with oxidation numbers: Try magnesium and chlorine Add enough ions together so that the charges equal zero

2 Ways to Write Ionic Compounds 3. Add up the ions and write the compound as a formula 4. Name:

2 Ways to Write Ionic Compounds Write the element symbols with oxidation numbers: Try magnesium and chlorine Cross the numbers, not the signs

2 Ways to Write Ionic Compounds 3. Reduce the ratio and drop any 1’s 4. Name: