2.5. Simple molecules and covalent bonds
A subsection of Chemistry, 0620, through 2. Atoms, elements and compounds
Listing 10 of 177 questions
Complete the table to show the electronic structure of the atoms and ions. electronic structure F 2,7 Si Ca2+ N3– Predict the formula of the compound formed between Ca2+ and N3–. Draw a dot-and-cross diagram to show the electron arrangements in the two ions present in lithium chloride, LiCl. Show outer shell electrons only. Include the charges on the ions. Sulfur dichloride, SCl 2, is a covalent compound. It has the structure Cl –S–Cl. Draw a dot-and-cross diagram to show the electron arrangement in a molecule of sulfurdichloride. Show outer shell electrons only. In terms of attractive forces, explain why LiCl has a higher melting point than SCl 2. Suggest the identity of a covalent compound with a higher melting point than LiCl.
0620_w17_qp_42
THEORY
2017
Paper 4, Variant 2
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Nitrogen molecules are diatomic. State the meaning of the term diatomic. State the percentage of nitrogen in clean, dry air. Ammonia has a simple molecular structure. Complete to show the dot-and-cross diagram for a molecule of ammonia. Show outer shell electrons only. N H H H Sodium chloride has a giant ionic structure of positive and negative ions. State the general name given to any positive ion. State one physical property of an ionic compound. Graphite is used as an electrode. State one other use of graphite. Choose the correct statement that describes the structure and bonding in graphite. Tick (✓) one box. simple covalent molecule giant ionic simple ionic giant covalent
0620_w24_qp_31
THEORY
2024
Paper 3, Variant 1
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Hydrogen chloride has a simple molecular structure. State two physical properties of a compound with a simple molecular structure. Hydrogen chloride is a molecule with a covalent bond. Complete this sentence about a covalent bond. A covalent bond is formed when two atoms share a pair of . Complete to show the dot-and-cross diagram for a molecule of hydrogen chloride. Show outer shell electrons only. Cl H Zinc chloride has a giant ionic structure of positive and negative ions. State the general name given to any negative ion. Diamond is used for jewellery. State one other use of diamond. Choose the correct statement that describes the structure and bonding in diamond. Tick (✓) one box. simple covalent molecule giant covalent simple ionic giant ionic
0620_w24_qp_32
THEORY
2024
Paper 3, Variant 2
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Oxygen, water and ethene have simple molecular structures. State the percentage of oxygen in clean, dry air. Complete to show the dot-and-cross diagram for a molecule of water. Show outer shell electrons only. O H H Ethene is a small molecule used to make polymers. State the name of the polymer formed from ethene. Complete this sentence about polymers. Polymers are large molecules built up from many smaller molecules called . Potassium chloride is an ionic compound. State two physical properties of ionic compounds. Choose the correct statement that describes ionic bonding. Tick (✓) one box. It is a weak electrostatic attraction between anions and cations. It is a weak electrostatic attraction between cations. It is a strong electrostatic attraction between anions. It is a strong electrostatic attraction between cations and anions.
0620_w24_qp_33
THEORY
2024
Paper 3, Variant 3
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Fluorine is a GroupVII element. Fluorine forms compounds with metals and non-metals. Predict the physical state of fluorine at room temperature and pressure. Fluorine exists as diatomic molecules. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of fluorine. Show outer shell electrons only. F F  Write a chemical equation for the reaction between sodium and fluorine. Explain why chlorine does not react with aqueous sodium fluoride. Tetrafluoromethane and lead(fluoride are fluorides of GroupIV elements. Some properties of tetrafluoromethane and lead(fluoride are shown in the table. property tetrafluoromethane lead(fluoride formula CF4 melting point / °C –184 boiling point / °C –127 conduction of electricity when solid non-conductor non-conductor conduction of electricity when molten non-conductor good conductor What is the formula of lead(fluoride? What type of bonding is present between the atoms in tetrafluoromethane? What type of structure does solid lead(fluoride have? Explain, in terms of attractive forces between particles, why lead(fluoride has a much higher melting point than tetrafluoromethane. In your answer refer to the types of attractive forces between particles and their relative strengths. Tetrafluoroethene is an unsaturated compound with the formula C2F4. Tetrafluoroethene is the monomer used to make the polymer poly. What is meant by the term unsaturated ? Describe a test to show that tetrafluoroethene is unsaturated. test observations  Draw the structure of a molecule of tetrafluoroethene. Show all of the atoms and all of the bonds.  Tetrafluoroethene can be polymerised to form poly. Draw one repeat unit of poly. Show all of the atoms and all of the bonds.  Deduce the empirical formula of: tetrafluoroethene poly.  
0620_m19_qp_42
THEORY
2019
Paper 4, Variant 2
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Questions Discovered
177