Calcium Hydroxide

1 a The diagram shows the parts of a hydrogen atom.

[pic] Use words from the list to label the diagram. electron group nucleus symbol (2) b Hydrogen can be used as a clean fuel for cars. i When hydrogen burns in air, it reacts with another element. Complete the word equation for this reaction. hydrogen + ................... → water (1) ii Suggest one reason why hydrogen is called a clean fuel.

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AQA, 2008

2 Use a periodic table to help you to answer this question. Oxygen is in Group 6 of the periodic table. a i How many protons are in an atom of oxygen?

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ii How many electrons are in an atom of oxygen?

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b Chlorine is in Group 7 of the periodic table. Complete the electronic structure of chlorine: 2, ........... (1) c Fluorine is also in Group 7. Explain why in terms of electronic structure.

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d Neon and argon are in Group 0 of the periodic table. They are very unreactive elements. What does this tell you about their electronic structures?

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3 When calcium carbonate is heated it decomposes. The equation for this reaction is: CaCO3 → CaO + CO2 a Use numbers from the list to complete the sentences. 2 3 4 5 6 i The number of products in the equation is ....... (1) ii The formula CaCO3 shows that calcium carbonate was made from ....... different elements. iii The equation is balanced because there are ....... atoms on both sides.(1) (3) b Other metal carbonates decompose in a similar way. i Name the solid produced when zinc carbonate decomposes.

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ii Name the gas produced when copper carbonate decomposes.

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4 Farmers can use calcium hydroxide to neutralise soils that are too acidic. Limestone is mainly calcium carbonate, CaCO3. Limestone is used to make