Ionic Versus Covalent Compounds Metal + Non-Metal atoms “Give & Take” electrons Covalent Non-Metal atoms ONLY! “Share” electrons How to tell if a compound is ionic or covalent? Ask...... Is there a metal? Yes = Ionic No = Covalent

Ionic Compounds Ionic are made up of positive and negative ions organized in a pattern Negative-positive attract. Negative-negative and positive-positive repel. Ionic compounds form solid crystals Ionic compounds are like a solid stack of bricks. A salt shaker contains thousands of small pieces of NaCl. compounds Na+ = positive ion Salt, NaCl Cl- = negative ion See pages 184 - 185

Covalent Molecules Covalent share electrons. molecules There is generally no order to the formation of covalent molecules. These molecules clump together as solids, liquids or gases. Covalent molecules are like a play-pit full of plastic balls. Each plastic ball = 1 covalent molecule of H2O molecules Water, H2O See pages 184 - 185

Naming an Ionic Compound Ionic compounds are always composed of a metal and a non-metal. The name of an ionic compound = positive ion + negative ion-ide. For example, an ionic compound forms between magnesium and oxygen. The positive ion is the first part of the name, magnesium. The negative ion forms the root of the second part of the name, oxygen. Add -ide to the end of the name to form magnesium oxide. Non-Metal Metal Metal (2+) Non-Metal (2-) Magnesium oxide is used as a drying agent. See pages 186 - 187 (c) McGraw Hill Ryerson 2007

You try… Calcium nitride What is the name of Ca3N2? What is the positive ion? Ca = calcium What is the negative ion? N = nitrogen Drop the end of the negative ion and add -ide. What is the name of Ca3N2 ? Calcium nitride

Practice Problems

Names of Covalent Compounds Covalent compounds, also called molecules, rely on the chemical formula to reveal the components of the molecule. Covalent compounds are made up of two or more non-metals. Names may reveal the components, but often they do not… For example... The name of the compound C2H6O is ethanol Another example is C12O22H11 which is Sucrose (table sugar) See page 193

Naming Binary Covalent Compounds Binary covalent compounds (two non-metal atoms) use a system of prefixes. Write the most metallic atom (farthest left) first Add -ide to the end of the second atom’s name Add a prefix before each atom’s name to indicate the number of atoms in the molecule. (Do not add a prefix to the first atom if there is only 1) For example: CO = carbon monoxide, CO2 = carbon dioxide What is the name of the molecule Si3P6? Trisilicon hexaphosphide See pages 194 - 195

You Try... Tetraphosphorus decasulphide What is the name of P4S10? What is the most metallic atom? P = Phosphorus Add –ide to the end of the second atom’s name S = Sulphide Add prefixes before each atom 4 Phosphorus = tetraphosphorus 10 Sulphur = decasulphide What is the name of P4S10 ? Tetraphosphorus decasulphide

Practice Problems