Topic 6: Chemical Compounds Continued Remember there are two types of chemical compounds molecular/covalent and ionic. When an atom gains or loses electrons it is not neutral it possesses a charge and becomes an ion. When an atom loses an electron it becomes positively charged. When an atom gains an electron it becomes negatively charged. Examples: How many electrons have the sodium, calcium, chlorine and boron ions lost or gained?

Example: How many protons and electrons do each of the ions in the previous example have? When ions bond they create ionic compounds. Ionic Compounds a metal, (positive) with a non – metal, (negative) contain ions in solution can conduct electricity solids at room temperature

Naming Ionic Compounds Write the name of the metal ion first. Write the name of the non – metal second changing the end to “ide”. NEVER USE PREFIXES FOR IONIC COMPOUNDS Example: Write the name for the following ionic compounds. CaCl2 ZnS NaCl Sc2O3 NaF Na2S LiCl

Writing the Chemical Formula for Ionic Compounds Write the symbol of the metal first. Give it the charge of the non – metal as a sub – script. Write the symbol of the non – metal second. Give it the charge of the metal as a subscript. Reduce the charges if possible. ***Always “swap” charges*** Example: Write the formula for the following ionic compounds. lithium chloride zinc chloride strontium nitride calcium oxide

Polyatomic ions A polyatomic ion is a charged species that has two or more atoms bonded together. When you name ionic compounds with polyatomic ions use the same procedure but DO NOT change the name of the polyatomic ions. Example: Name the following: (NH4)2O Be(Cl4)2 (NH4)2(Cr2O7)

Polyatomic ions Continued When you find the chemical formula for polyatomic ionic compounds use the same procedure but make sure to put the polyatomic ion(s) in brackets. Example: Find the formulas for: ammonium phosphide lithium carbonate magnesium sulfate ammonium phosphate