Negative Ions Formation Negative ions are formed when atoms gain electrons to be like noble gas configurations. Fluorine 1s 2 2s 2 2p 5 becomes 1s 2 2s 2 2p 6 like neon…. 2s 2 2p 6 makes an octet. When negative ions form, we change the atom name to have an –ide ending… F - is the formula and the ion name is fluoride ion. Positive ions just take the atom name with ion. Nonmetals gain electrons to become negative ions.

Properties of Ionic Compounds Made of a metal and nonmetal Crystalline solids with high melting points Ionic compounds conduct as an aqueous solution…called electrolytes. Form crystals which break as solids when struck. (See p 215.) The energy to break one mole of ions, of an ionic compound, is called lattice energy.

7-3 Names and Formulas for Ionic Compounds To write formulas for ionic compounds, … 1.Write the + ion, then the – ion. 2.Write the charges for each ion. 3.Criss- cross the number values only. 4.Reduce sub-numbers.

To Name Ionic Compounds… Say the name of the positive ion. (without ion) If the positive ion is on the ‘Cops in a Mercury chart, include a Roman Numeral. Say the name of the negative ion. (without ion) All ionic compounds with 2 capitol letters end in ide.

Polyatomic Ions The ions that have 2 or more elements are called polyatomic ions. See your chart on the back of your periodic table. Polyatomic ions work just like monatomic ions. We put parentheses around polyatomic ions. Learn your polyatomic ion chart for quiz 2. Most polyatomic ions have oxygen and are called oxyanions.

Polyatomic Ions The oxyanion with the fewer number of oxygens ends in –ite. The oxyanion with the higher number of oxygens ends in –ate. NH 4, ammonia, is our only + polyatomic ion. Look at your polyatomic ion chart. Remember the 2- column by … Oxy was late, she sulked and sulked, ‘cause her car ‘been’ ate…her car’been’ ate, isn’t this silli- Cate? This helps you remember the 2- column. Phosphate and phosphite are the only 3- ions, so this leaves ony the 1- column.