Structure, bonding and the properties of matter: แบบฝึกหัด

A student is investigating the properties of a material. They find that the material has a giant ionic lattice structure. Which of the following is a characteristic property of this type of substance?

Substances with simple molecular structures, such as methane \( (CH_4) \), are typically gases or liquids at room temperature. What is the reason for their low boiling points?

In the structure of graphite, each carbon atom is bonded to three other carbon atoms. Which statement correctly explains why graphite is soft and can be used as a lubricant?

Which of the following statements correctly describes the arrangement and bonding in a metal?

When sodium reacts with chlorine to form sodium chloride, an ionic bond is created. Which statement best explains the nature of this bond?

Ionic compounds, such as sodium chloride, have very high melting points. Using your knowledge of structure and bonding, explain why a large amount of energy is needed to melt these substances.

Explain why graphite is soft and can be used as a lubricant, whereas diamond is extremely hard, even though both are composed entirely of carbon atoms.

(a) Magnesium oxide is an ionic compound formed from the reaction between magnesium atoms and oxygen atoms. Describe, in terms of electrons, what happens when a magnesium atom reacts with an oxygen atom to form magnesium oxide. You should include the charges on the ions formed.

(b) Magnesium oxide has a very high melting point of \(2852\,^{\circ}\text{C}\). Explain why magnesium oxide has such a high melting point by referring to its structure and bonding.

(c) Graphite is a form of carbon that is used in electrodes because it can conduct electricity. Explain why graphite can conduct electricity but diamond cannot, even though both consist of only carbon atoms.