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Science C2 Topic 4
Edexcel GCSE additional science chemistry: groups in the periodic table
Question | Answer |
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How do ionic compounds form and what is the relative melting/ boiling point, relative solubility in water and ability to conduct electricity? | Formed when a metal loses electrons to become a cation and a non-metal gains electrons to become an anion. High melting and boiling points. Many are water soluble. Conduct electricity when molten/ in a solution. |
How do simple molecular covalent compounds form and what is the relative melting/ boiling point, relative solubility in water and ability to conduct electricity? | Atoms share electrons to gain full outer shells and are joined by covalent bonds. Low melting and boiling points. Some are water soluble. Don't conduct electricity. |
How do giant molecular covalent compounds form and what is the relative melting/ boiling point, relative solubility in water and ability to conduct electricity? | Billions of atoms share electrons to get full outer shells and are held together by covalent bonds. High melting/ boiling points. None are water soluble. Don't conduct electricity (apart from graphite) |
What is the structure of metals? | Metals are a regular arrangement of positive metal ions surrounded by a 'sea of electrons' that are delocalised and move around the positive ions randomly |
What are some properties of metals + reasons? | * malleable because layers can slide without fracturing the structure as the delocalised electrons maintain strong bonds * good electrical conductors as the delocalised electrons carry the charge. * good heat conductors as electrons transfer the energy |
Where are transition metals found in the periodic table and what are their properties? | They are found in the central block of the periodic table and they form coloured compounds and have high melting points |
Where are alkali metals found in the periodic table- what does this show? | Group 1- this shows they have 1 electron in their outer shell |
What are some properties of alkali metals? | * soft metals. *solid at room temp but comparatively low boiling point. |
What is formed when an alkali metal reacts with water? | A metal hydroxide + hydrogen gas (this is exothermic) |
Does the reactivity alkali metals increase or decrease as you go down the group and why? | Increase, because the outer electrons of the lower elements are further from the nucleus and aren't held on as strongly, as the forces between the positive and negative charges are weaker |
Where are halogens found in the periodic table- what does this show? | They are found in group 7 of the periodic table, so they have 7 electrons in their outer shells |
What is the colour and state of fluorine at room temperature? | Pale yellow, gas |
What is the colour and state of chlorine at room temperature? | Green, gas |
What is the colour and state of bromine at room temperature? | Brown, liquid |
What is the colour and state of iodine at room temperature? | Grey, solid |
What is formed when halogens react with metals? | Metal halides |
Does the reactivity halogens increase or decrease as you go down the group? | Decrease |
What is formed when halogens react with hydrogen? | Hydrogen halides, which dissolve in water to form acids |
What happens in a displacement reaction? | A more reactive halogen will displace a less reactive halide in an aqueous solution |
Where are noble gases found in the periodic table- what does this show? | Group 0/8- this means they have a full outer shell so are inert and react with very little |
Explain the discovery of the noble gases | Scientists noticed that nitrogen produced from a reaction was less dense than nitrogen from air by removing other gases. They hypothesised that there was a denser gas with the nitrogen from the air. They carried out experiments and discovered argon. |
What are some uses of noble gases? | Xenon and argon were formerly used in filament lamps as they are inert. Argon is used in fire-extinguishing as it is nonflammable. Helium has a low density so balloons and airships are filled with it. Argon and helium are used in welding as they are inert |
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