CHEMISTRY FORM 2
- 1.1 Structure of the atom
- 1.2 Atomic Number and Mass Number
- 1.3 Isotopes
- 1.4 Energy levels and electron arrangement
- 1.5 Development of the Periodic Table
- 1.6 Relative Atomic Mass and Isotopes
- 1.7 Ion Formation
- 1.8 Chemical Formulae
- 1.9 Chemical Equations
- 2.1 Alkali metals (Group I elements)
- 2.2 Alkali Earth Metals (Group II elements)
- 2.3 Halogens (Group VII elements)
- 2.4 Noble gases (Group VIII elements)
- 2.5 Properties and Trends Across the Periodic Table
- 3.1 Bond
- 3.2 Ionic bond
- 3.3 Giant ionic structure
- 3.4 Covalent bond
- 3.5 Co-ordinate bond
- 3.6 Molecular structures
- 3.7 Giant covalent structures
- 3.8 Metallic Bond
- 3.9 Types of bond across a period
- 3.10 Oxides of elements in Period 3
- 3.11 Chlorides of Period 3 elements
- 4.1 What is a salt?
- 4.2 Types of salt
- 4.3 Solubility of salts in water
- 4.4 Methods of preparing salts
- 4.4.1 Reacting a Metal with an Acid
- 4.4.2 Reacting an Acid with a Base (Neutralization)
- 4.4.3 Reacting an Acid with a Carbonate (or hydrogencarbonate of metal)
- 4.4.4 Combining elements Directly (Direct Combination of elements)
- 4.4.5 Precipitation (Double decomposition)
- 4.5 Action of heat on salts
- 4.6 Uses of salts
- 5.1 Electrical conduction
- 5.2 Electrical conductivity of molten substances
- 5.3 Electrical conductivity of substances in aqueous state
- 5.4 Electrolysis
- 5.5 Applications of electrolysis
- 6.1 Allotropes of carbon
- 6.2 Chemical properties of carbon
- 6.3 Carbon (IV) oxide
- 6.4 Carbon (II) oxide (CO)
- 6.5 Large scale production of sodium carbonate and sodium hydrogencarbonate
- 6.6 Effect of carbon (II) oxide and carbon (IV) oxide on the environment
- 6.7 Carbon cycle
Chemical Bonding and Structure: Ionic bond
3.0 Chemical Bonding and Structure
3.2 Ionic bond
As the name suggests, ionic bond is an attraction between ions (not a definition).
Questions 3.2(a)
- What must be true about the charges on ions for them to attract each other?
- From Topic 2, which groups of the Periodic Table form positive ions (cations)? Write the formulae of six (6) examples of cations from these groups.
- Which groups of the Periodic Table form negative ions (anions)? Write the formulae of six (6) examples of anions from these groups.
- Write the names and formulae of two examples of compounds which have ionic bonds.
Answers to Questions 3.2(a)
Atoms of elements in Groups I to III and other metals combine with any elements in Groups V to VII through ionic bonds. Ionic bond is the attraction between positive and negative ions formed when some atoms lose and others gain electrons. Table 3.1 presents examples of ions and the ionic compounds they form.
Table 3.1: Examples of ions and ionic compounds they form
Questions 3.2(b)
- Name all the ionic compounds indicated in the last column of Table 3.1.
- Four atoms and their electronic configurations are A (2:8:4); G (2:8:2), R (2:8), and Q (2:8:7). The letters used are not the actual chemical
symbols.
Which two of the elements would combine with each other through ionic bond? - Write the formulae of the ions they form. Use the same letters given.
- Write the formula of the ionic compound they form.
Answers to Questions 3.2(b)
Naming of compounds
You may have noticed, all along, that the name of a compound begins with a metal or positively charged ion such as NH4+ and H+ if there is one. Examples are sodium chloride, magnesium nitride, copper (II) oxide, silver nitrate, ammonium carbonate, and hydrogen chloride. Valencies are indicated for elements that show variable valencies. Examples are copper (I or II), carbon (II or IV), iron (II or III), lead (II or IV), manganese (II or IV), phosphorus (III or V), and sulphur (IV or VI).
For compounds of non-metals only, name of the element in the lower group (less electronegative) comes first. Examples are carbon (II) oxide, carbon (IV) oxide, silicon (IV) oxide, phosphorus (V) oxide, and phosphorus (III) chloride. Carbon, silicon and phosphorus come before oxygen and chlorine.
It is rare for elements within the same group to react with each other. But when they do, the less electronegative element(less reactive and lower in the group) comes first. Examples are sulphur (IV) oxide and sulphur (VI) oxide.