Naming Ionic Compounds Science 10

Simple Ionic Compounds Let’s look at this example: KBr Name the metal (cation) first Potassium Name the non-metal (anion) next, end it with –ide Bromine becomes bromide Put together: Potassium bromide

Practice Na2O Sodium Oxide Name the metal: Name the non-metal: Put them together to get: Sodium Oxide Note: It takes two Na+ to combine with one O2- to make a neutral compound!

If you’re given the name, can you write the formula? Writing Formulae If you’re given the name, can you write the formula? Strontium nitride Strontium is Sr2+ Nitride is N3- We must combine them to be equal to zero Need 3 Sr2+ to combine with 2 N3- Answer is Sr3N2

Multivalent Ionic bonding Some elements are capable of forming more than one ion Example: Copper can be Cu+ or Cu2+ meaning it can donate 1 or 2 electrons We show this on the periodic table by a split cell showing both charges

There is an option of Fe2+ and Fe3+ When compounds are made with multivalent elements, we must choose or indicate which charge we are referring to in the chemical equation. Look at Iron There is an option of Fe2+ and Fe3+ FeO would be called Iron (II) oxide It takes Fe2+ to balance out charges with O2- We indicate the optional charge with roman numerals; 2= II, 3=III, 4=IV and so on The roman numeral is put after the cation

Practice Naming FeCl2 MnO Fe2O3 TiO2

Practice & Homework 1. Practice writing ionic formulae with Investigation 2 2. Practice naming ionic compounds with Investigation 3

Naming With Polyatomic Ions

Polyatomic Ions Polyatomic ions are ions that contain two or more atoms. They are electrically charged, which means that they are always looking at gaining or losing one or more electrons. So, polyatomic ions basically look like molecules (only contain non-metals), but with a charge.

Most polyatomic ions are anions, meaning they have more electrons than the neutral atoms that are in the ion. Hydroxide (OH-) has one extra electron beyond what the neutral oxygen and hydrogen atoms would have Although most are anions, there are some, which are cations. The most common is NH4+ (ammonium).

Naming with Polyatomic Ions It is the same for naming ionic compounds but you must use the names of the polyatomic ions. The endings will not change to –ide Examples: LiOH NH4Cl BaSO3

Writing Formula’s When there is more than one of the polyatomic ion needed you must place it in brackets Ex. Lithium hydroxide LiOH No brackets because Li+ and OH- balance in a 1:1 ratio Ex. Calcium hydroxide Ca(OH)2 Use brackets because Ca2+ needs 2 OH- in order to balance

Try Some Write the name or formula for the following: NaOH HCN Magnesium nitrate CaCO3

Practice & Homework Complete Investigation 4