chemistry

• 1.Define the keyword atom.

  The smallest part of an element. 2. Define the keyword element.

  Made from only one type of atom.
• 4. Explain what the mass number and atomic number tell us. Atomic number = Protons = Electrons Mass number = Protons + Neutrons in the nucleus
• What is the mass of an electron? 1/ 2000 or Very small 10. What is the charge of an electron? - 1
• 16. What is the maximum number of electrons that can fill the first shell? 2 17. What is the maximum number of electrons that can fill the second shell? 8
• 19. What group of the periodic table is oxygen in and why? Group 6 as 6 electrons in outer shell. 20. What group of the periodic table is magnesium in and why? Group 2 as 2 electrons in outer shell 21. What group of the periodic table is chlorine in and why? Group 7 as 7 electrons in outer shell 22. Why are the noble gases all in group 0? Full outer shell of electrons.
• James Chadwick


  Discovered that the nucleus of an atom contains neutrons
• The atom has a tiny positive nucleus at its centre
• The atom is mostly empty space
• Plum pudding model

  Positively charged sphere with negatively charged electrons embedded in it
• Alpha particles

  Particles that passed straight through the plum pudding model
• Most of the alpha particles passed straight through
• A small proportion of particles were deflected/scattered by large angles
• Niels Bohr


  Suggested that electrons occupy energy levels (shells)
• Define the keyword compound . Two or more different elements bonded together. 8. Define the state symbols (s), (l), (g), (aq). (s) = solid, (l) = liquid, (g) = gas, (aq) = aqueous 9. Describe simply what is meant by the state symbol (aq). Dissolved in water.
• Define the keyword mixture . Two or more elements or compounds not chemically combined.
• Which separating technique is used to obtain a pure dry solid crystal of a dissolved substance? Crystallisation
• 5. What is the mass of a proton? 1
• 7. What is the mass of a neutron? 1
• What is the charge of a neutron? 0
• 11. What fraction of the atomic radius, is the radius of the nucleus of an atom? 1/ 10,000 th
• 17. Which separating technique is used to separate a mixture of colours or food additives? Chromatography
• 18. Which separating technique is used to separate mixtures of liquids with different boiling points? Distillation
• 19. What is the first stage of distillation? The mixture of liquids is heated
• 20. What is the second stage of distillation? The substance with the lowest boiling point evaporates
• 13. Why is separating a mixture a physical process ? They do not result in a chemical reaction.
• 14. Name four methods of separating mixtures. Filtration, Crystallisation, Chromatography, Distillation.
• 15. Which separating technique is used to separate a solid from a liquid? Filtration