Chapter 7 – Materials

Consider the following statements and click to reveal the answer.

1. How are protons and neutrons the same/different?

Answer:

Both are found in the nucleus of an atom and both have an atomic mass of 1. Protons have a positive charge whereas neutrons are electrically neutral.

2. What is the atomic mass of Sulphur, and how many protons and neutrons are in its nucleus?

Answer:

Sulphur has an atomic mass of 32. The nucleus contains 16 protons and 16 neutrons.

3. What is the difference between ionic and covalent bonding? 

Answer:

Ionic bonding occurs when electrons are removed or added to an atom; covalent bonding is when electrons are shared.

4. How is solid gold chemically different from liquid gold?

Answer:

It isn’t chemically different; it is physically different.

5. In terms of electrons and the periodic table:

  1. What do argon, helium and neon have in common?
  2. What do sodium and potassium have in common?
  3. How would an oxygen ion be represented?
  4. Show the covalent bonding in N2 using a dot and cross diagram.
  5. What kind of bonding will there be in magnesium oxide (MgO)? Show in diagrammatic form what a single molecule would look like.
  6. What kind of bonding will there be in ethanol (C2H5OH)? Show in diagrammatic form what a single molecule would look like.

Answer:

  1. Each of these elements has a complete electron shell (or stable electron configuration). They are called the ‘noble gases’.
  2. They are both elements with only one electron occupying the shell furthest from the nucleus.
  3. An oxygen ion would have two excess electrons and so would be represented as O2–.

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  5. MgO – ionic bonding.

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  6. C2H5OH – covalent bonding.

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