Retrieval Practice
Covalent bonding (Small / simple molecules)
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Q1. What are the particles involved in covalent bonding? (1)
Non-metal atoms which share pairs of electrons.
Q2. How many electrons does hydrogen atom share? Why? (2)
1 electron
A hydrogen atom is in group 1, so it needs 1 more electron to achieve a full outer shell of 2 electrons.
(Hydrogen needs to fill in its first shell that holds maximum 2 electrons)
Q3. How many electrons do group 7 atoms share? Why? (2)
1 electron each
The atoms in group 7 have already 7 electrons on the outer shell so they need 1 more electron to achieve a full outer shell of 8 electrons.
(the other 6 electrons are not shared)
Q4. How many electrons do group 6 atoms share? Why? (2)
2 electrons each
The atoms in group 6 have already 6 electrons on the outer shell so they need 2 more electrons to achieve a full outer shell of 8 electrons.
(the other 4 electrons are not shared)
Q5. Describe the structure of substances made of simple molecules. (2)
There are strong covalent bonds between the non-metal atoms in the molecule,
and weak intermolecular forces between the molecules.
Q6. Name 2 properties of simple molecules. (2)
Low melting and boiling points.
Do not conduct electricity.
Q7. Explain why simple molecules have a low melting and boiling point. (2)
The intermolecular forces between the molecules are weak,
so little energy is needed to overcome these forces and separate the molecules.
Q8. Draw the dot and cross diagram for hydrogen molecule (H2). (2)
Q9. Draw the dot and cross diagram for fluorine molecule (F2). (2)
Q10. Draw the dot and cross diagram for chlorine molecule (Cl2). (2)
Q11. Draw the dot and cross diagram for oxygen molecule (O2). (2)
Q12. Draw the dot and cross diagram for nitrogen molecule (N2). (2)
Q13. Draw the dot and cross diagram for ammonia molecule (NH3). (2)
Q14. Draw the dot and cross diagram for methane molecule (CH4). (2)
Q15. Draw the dot and cross diagram for water molecule (H2O). (2)
Q16. Draw the dot and cross diagram for carbon dioxide molecule (CO2). (2)
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