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Science C2 Topic 2
Edexcel GCSE additional science chemistry: ionic compounds
Question | Answer |
---|---|
What is an ion? | An ion is an atom or a group of atoms that have gained or lost electrons so have a positive or negative charge |
How is an ionic bond formed? | By the transfer of electrons from a metal to a non-metal causing them both to have full outer shells and be in the most stable position possible |
What does a suffix of -ide show about a compound? | There is an ionic bond between a metal and a non-metal |
What does a suffix of -ate show about a compound? | There is an ionic bond between three elements, one of which is oxygen |
Use a dot and cross diagram to predict the ionic bonding of sodium chloride | NaCl |
Predict the ionic bonding of potassium nitrate | K3N |
Predict the ionic bonding of calcium fluoride | CaF2 |
What are some properties of ionic compounds? | * relatively high melting/ boiling temp * crystalline structure at RTP * lattice structure * conduct electricity when molten/ in a solution * many are soluble |
What are the solubility rules for: nitrates and sulphates? | All nitrates are soluble. All sulphates are soluble apart from calcium, lead and barium. |
What are the solubility rules for: bromides and iodides? | All bromides and iodides are soluble apart from silver and lead. |
What are the solubility rules for: carbonates and hydroxides? | All are insoluble apart from ammonium, potassium, sodium |
What is a precipitation reaction? | Where an insoluble salt is produced in a chemical reaction where the reactants are both water soluble |
What is a barium meal and why does it work? | It is a meal containing barium sulphate given to X-ray patients so the digestive system shows up on photos - it is opaque to X-rays and is safe to use as the toxic barium salts are insoluble so can’t dissolve into the blood stream |
How do you test for cations? | Flame tests- potassium goes lilac, calcium goes red, sodium goes yellow and copper goes green |
What is spectroscopy? | A type of flame test to test for very small amounts of elements- this was how rubidium and caesium were discovered |
How do you test for anions? | chloride: add dilute nitric acid & silver nitrate solution to chloride salt solution- a white precipitate forms. Sulphate: add dilute hydrochloric acid & barium chloride solution to a sulphate salt solution- white precipitate. Carbonate + acid -> CO2 (g) |