Level: JHS, Basic 9 | Subject: Integrated Science | Strand: Diversity of Matter | Topic: Chemical Bonding (Ionic and Covalent)
Read the summary notes first: Basic 9 Integrated Science Summary Notes: Chemical Bonding
Test Yourself: 20 Objective Questions
Tick one answer for each question, then press Review answer. If your answer is wrong, it will be marked first, then the correct answer will show in green.
Essay Questions
- Explain how sodium (atomic number 11) and chlorine (atomic number 17) combine to form sodium chloride. (6 marks)
- Describe how the atoms in a water molecule (H2O) are held together. (5 marks)
- State three differences between ionic compounds and covalent compounds. (6 marks)
- Why do noble gases such as neon rarely form bonds? Name two noble gases. (4 marks)
- Explain why solid sodium chloride does not conduct electricity but molten sodium chloride does. (4 marks)
Essay Questions: Marking Guide for Teachers and Parents
- (6 marks) Sodium has the arrangement 2,8,1 and loses 1 electron (1). It becomes a positive ion, Na+ (1). Chlorine has 2,8,7 and gains 1 electron (1). It becomes a negative ion, Cl- (1). The opposite charges attract each other strongly (1). This attraction is an ionic bond and the compound is NaCl (1).
- (5 marks) It is a covalent bond between non-metal atoms (1). Oxygen has 6 outer electrons and needs 2 more (1). Each hydrogen atom has 1 electron and needs 1 more (1). Oxygen shares one pair of electrons with each of the two hydrogen atoms (1). Every atom then has a full outer shell (1).
- (6 marks) Any three differences, 2 marks each. Ionic compounds form between a metal and a non-metal, but covalent compounds form between non-metals. Ionic compounds have high melting points, but covalent compounds have low melting points. Ionic compounds conduct electricity when molten or dissolved, but covalent compounds do not conduct.
- (4 marks) Their outer shells are already full (2), so they have no need to lose, gain or share electrons. Two examples such as helium, neon, argon (1 mark each).
- (4 marks) In the solid, the ions are held in fixed positions (1), so there are no free moving charges (1). When melted, the ions are free to move (1) and they carry the electric current (1).
Education Always (education.inspiringalways.com). Original practice questions, not official WAEC or BECE questions.