Methanal, $$$\mathrm{CH}_{2} \mathrm{O}$$$, has a boiling point of $$$-19^{\circ} \mathrm{C}$$$. At $$$-20^{\circ} \mathrm{C}$$$, the liquid methanal is a non-conductor of electricity. In a sample of methanal, each atom of carbon, hydrogen and oxygen has noble gas electronic configuration. Each atom has achieved this electronic configuration in one of three ways: - gaining electrons - losing electrons - sharing electrons. Which statement describes the bonding between the carbon atom and the oxygen atom in methanal?

The carbon atom and the oxygen atom share four electrons.

The carbon atom and the oxygen atom share two electrons.

Carbon is a negative ion and oxygen is a positive ion. These two ions attract each other.

Carbon is a positive ion and oxygen is a negative ion. These two ions attract each other.

Chemistry

IGCSE&ALevel

CAIE

Exam No：0620_m24_qp_22 Year：2024 Question No：6

Answer:

2.5.1. State that a covalent bond is formed when a pair of electrons is shared between two atoms leading to noble gas electronic configurations

2.5.2. Describe the formation of covalent bonds in simple molecules

2.5.3.1. low melting points and boiling points

2.5.3.2. poor electrical conductivity

2.5.4. Describe the formation of covalent bonds in simple molecules

2.5.5.1. low melting points and boiling points in terms of weak intermolecular forces (specific types of intermolecular forces are not required)