Page 68 - Chemistry_Form_2

Chemistry
for Secondary Schools

Ca 2 Cl 1

1 2
CaCl
FOR ONLINE READING ONLY
2
The formula of the chemical compound is CaCl . The compound contains two
chlorine atoms and one calcium atom. 2

Example 3.5

Give the formula of the compound of aluminium and sulfate.

Step 1: Al SO
4
Step 2: Al 3+ SO 2–
4
Step 3: Al 3 SO 2
4
Step 4: Al 3 SO 2
4

2 3

Al (SO )
2 4 3
The chemical formula is Al (SO ) .
2 4 3

Exercise 3.3

1. Write the steps used to arrive to the following chemical formulas of the
compounds:

(a) MgCl (b) Na SO (c) NH NO
2 2 4 4 3
2. Write down the chemical formula of each of the compounds formed by the
combination of the following elements:

(a) Potassium and chlorine

(b) Calcium and sulfur
(c) Lithium and fluorine

Student’s Book Form Two 61

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CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 61