CAIE IGCSE Chemistry Simple Molecules and Covalent Bonds

Practise drawing shared electron pairs in molecular structures and explaining melting point or conductivity by distinguishing bonds from intermolecular forces.

Exam points

draw single, double or triple shared pairs and include the correct non-bonding outer electrons
explain low melting or boiling points by weak forces between molecules, not weak covalent bonds
explain non-conduction by the absence of mobile ions or delocalised electrons in the molecules

Covered syllabus points

2.5.1—Covalent bond is formed when a pair of 2.5.2—Formation of covalent bonds in simple 2.5.3—Simple molecular compound properties 2.5.4—Formation of covalent bonds in simple 2.5.5—Simple molecular compound properties

[Maximum number: 3]

Fluorine is a Group VII element. Fluorine forms compounds with metals and non-metals.

(a)

Fluorine exists as diatomic molecules.

Complete the dot-and-cross diagram to show the electron arrangement in a molecule of fluorine. Show outer shell electrons only.

Figure for Question (a) — CAIE IGCSE Chemistry

[ 2 ]

(b)

Tetrafluoromethane and lead(II) fluoride are fluorides of Group IV elements. Some properties of tetrafluoromethane and lead(II) fluoride are shown in the table.

Table for Question (b) — CAIE IGCSE Chemistry

[ 1 ]

(i)

What type of bonding is present between the atoms in tetrafluoromethane?

[ 1 ]

[Maximum number: 1]

The table shows the melting points, boiling points and electrical conductivities of six substances, D, E, F, G, H and I.

Table for Question 2.5 Simple molecules and covalent bonds question 2 — CAIE IGCSE Chemistry

Identify the substance, D, E, F, G, H or I, which is:

a solid consisting of simple molecules at $25^{\circ} \mathrm{C}$ . ..... [1]

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Covered syllabus points

2.5 Simple molecules and covalent bonds question 1

Question (a)

Question (b)

Question (i)

2.5 Simple molecules and covalent bonds question 2