Bonding structure and the properties of matter

Carbon exists in different forms called allotropes. Which allotrope of carbon is a simple molecule with the formula C₆₀, forming a shape like a football?

The diagram represents part of the structure of graphite. Which structural feature is the reason that graphite conducts electricity?

The diagram represents part of the structure of graphite. Which structural feature is the reason that graphite is soft?

This question is about alloys. Solders are alloys of tin and lead. The solder in Figure 4 has 6 lead atoms for every 24 tin atoms. Determine the percentage of atoms that are lead atoms in the solder in Figure 4.

Explain why solder is harder than pure tin. Complete the sentences. Use Figure 4.\n\nIn solder the layers are distorted.\nThis is because the atoms of tin and lead have different ______.\nTherefore the layers cannot easily ______.

Describe what happens to the melting point of the solder as the percentage by mass of tin increases. Use data from Figure 5.

What is the melting point of pure tin? Use Figure 5.

What happens to the atoms in pure tin as the tin melts?

This question is about small particles. Which type of particle is often referred to as dust?

A spherical coarse particle has a diameter of 4000 nm. A spherical fine particle has a diameter of 200 nm. How many times larger is the diameter of the coarse particle than the diameter of the fine particle?

Figure 6 represents a cubic nanoparticle with side length 3 nm. The volume of the cubic nanoparticle is 27 nm³. Calculate:\n• the surface area of the cubic nanoparticle\n• the simplest whole number ratio of surface area : volume for the cubic nanoparticle.\nUse the equation: surface area of cubic nanoparticle = 6 × surface area of one face

Titanium oxide is used in some sun creams. Which is an advantage of using nanoparticles of titanium oxide rather than normal-sized particles of titanium oxide in sun creams?

Titanium oxide contains Ti⁴⁺ ions and O²⁻ ions. What is the formula of titanium oxide?

This question is about ionic compounds and electrolysis. Calcium chloride is an ionic compound. Calcium and chlorine react to produce calcium chloride. Describe what happens to calcium atoms and chlorine atoms when the ionic compound calcium chloride is formed.

This question is about iron. Iron is a metal. Describe how iron conducts thermal energy.

Pure iron is too soft for many uses. Explain why mixing iron with other metals makes alloys which are harder than pure iron.

The most common oxides of iron are Fe₂O₃ and Fe₃O₄. What is the ratio of the numbers of ions in Fe₃O₄?

Pure gold is 24 carat. Suggest two reasons why silver and copper are mixed with gold to make 9 carat gold rings.

The mixture of gases from the reactor cools in the condenser. Suggest why ammonia condenses but the other gases do not.