Ionic formulae and names MgO has a melting point of 2,852 C. (because of strong electrostatic forces Mg2+ and O2-) compared with sodium chloride 801 C

Key words/terms Polyatomic atoms Carbonate Nitrate Sulfate Hydroxide Students to copy down key words/terms and leave a line to add definition later in lesson January 1, 2019

Introduction We looked at forming ions last lesson and we can link this to both electronic structure and the periodic table 1+ 2+ 3+ 3- 2- 1- Teacher needs to explain that the group and therefore electronic structure dictate the charge the ion will have in this group. January 1, 2019

Naming ionic compounds Almost all ionic compounds have a two word name Cation Anion Ionic compound Sodium Chloride Sodium chloride Lithium Bromide Lithium bromide The ending of the anion is usually the part that changes, mostly to –ide. This tells us they contain only atoms from one element January 1, 2019

-ates and -ides -ides -ates Some common anions ending in –ide Chloride - 𝐶𝑙 − Fluoride - 𝐹 − Bromide - 𝐵𝑟 − Oxide - 𝑂 2− Hydroxide - 𝑂𝐻 − -ates contain oxygen and another element Carbonate - 𝐶𝑂 2− Sulphate - 𝑆𝑂 4 Nitrate - 𝑁𝑂 − 3 2- 3 January 1, 2019

Chemical formula Compound name MgO NaCl LiBr Ca Cl 2 NaOH Cu SO 4 Ca CO 3 Na NO 3 FeS Cu CO 3 Magnesium oxide Sodium chloride Lithium Bromide Calcium chloride Sodium hydroxide Copper sulfate Calcium carbonate Sodium nitrate Iron sulfide Copper carbonate January 1, 2019

Writing chemical formula Cations Anions +1 +2 +3 -1 -2 Lithium - 𝐿𝑖 + Magnesium - 𝑀𝑔 2+ Aluminium - 𝐴𝑙 3+ Chloride - 𝐶𝑙 − Oxide - 𝑂 2− Sodium - 𝑁𝑎 + Calcium - 𝐶𝑎 2+ Bromide - 𝐵𝑟 − Sulphide - 𝑆 2− Potassium - 𝐾 + Barium - 𝐵𝑎 2+ Iodide - 𝐼 − Sulfite - 𝑆𝑂 2− Ammonium - 𝑁𝐻 4 Iron (II) - 𝐹𝑒 2+ Nitrate - 𝑁𝑂 − Sulphate - 𝑆𝑂 4 Hydrogen - 𝐻 + Copper - 𝐶𝑢 2+ Hydroxide - 𝑂𝐻 − Carbonate - 𝐶𝑂 3 3 2- 3 2- Ionic compounds in symbols are called chemical formula, these save time and give us the correct ratio of elements present. We need the charge of both anion and cation to write them January 1, 2019

Writing chemical formula Step 1: write down the name Step 2 Write down the correct formula for each ion Step 3 balance the charges so that the compound is neutral Example Step 1: sodium sulphate Step 2: 𝑁𝑎 + and 𝑆𝑂 4 Step 3: 𝑁𝑎 + 𝑁𝑎 + 𝑆𝑂 4 (Notice we need 2 sodium to balance) Step 4: 𝑁𝑎 2 𝑆𝑂 4 2- 2- January 1, 2019

Alternative method – cross over 3 2 Al O This can be used to supply additional support for students who have difficulty balancing charge independently O Al 2 3 January 1, 2019