The table shows the physical properties of some elements.
| Element | Melting point (°C) | Density (g/cm3\text{g/cm}^3g/cm3) | Electrical conductivity | Tensile strength | Cost |
|---|---|---|---|---|---|
| W | low | low | good | low | low |
| X | high | high | good | high | high |
| Y | high | low | good | high | low |
| Z | high | low | poor | low | high |
Which element, W, X, Y or Z, would be best to use to make overhead cables for national electricity transmission? Explain your answer.
Define the term physical property.
An unknown element burns in oxygen to make a white powder of its oxide. Describe how you could test this oxide to find out if the element is a non-metal.
Magnesium is a metal. Magnesium has two common isotopes:
1224Mgand1226Mg \text{}^{24}_{12}\text{Mg} \quad \text{and} \quad \text{}^{26}_{12}\text{Mg} 1224Mgand1226MgComplete the table to show the atomic structure for each isotope of magnesium.
| Isotope | Number of protons | Number of neutrons | Number of electrons |
|---|---|---|---|
| Magnesium-24 | …………\dots\dots\dots\dots………… | …………\dots\dots\dots\dots………… | …………\dots\dots\dots\dots………… |
| Magnesium-26 | …………\dots\dots\dots\dots………… | …………\dots\dots\dots\dots………… | …………\dots\dots\dots\dots………… |
Magnesium reacts with oxygen gas, O2\text{O}_2O2, to form magnesium oxide, MgO\text{MgO}MgO. Write a balanced half equation for oxygen in this reaction.
Barium chloride solution, BaCl2\text{BaCl}_2BaCl2, reacts with sodium sulfate solution, Na2SO4\text{Na}_2\text{SO}_4Na2SO4. A white precipitate of barium sulfate, BaSO4\text{BaSO}_4BaSO4, is made. Write a balanced ionic equation to show the formation of barium sulfate. Include state symbols.