Across
- 4. a substance formed by the chemical combustion of two or more elements in fixed proportion.
- 5. the natural cycle by which rocks are pushed upwards, then eroded, transported, deposited, and possibly changed into another type of rock by conditions of temperature and pressure – these rocks may then be uplifted to enter a new cycle.
- 7. a regular three-dimensional arrangement of atoms, molecules or ions in a crystalline solid.
- 9. a subatomic particle with negligible mass and a charge of – 1.
- 10. a process occurring at the surface of a liquid, involving the change of state from a liquid into a vapor at a temperature below the boiling point.
- 14. term that describes a liquid, which evaporates easily; it is a liquid with a low boiling point having only weak intermolecular forces between the molecules in the liquid.
- 17. the temperature at which a liquid boils, when the pressure of the gas created above the liquid equals atmospheric pressure.
- 18. a chemical reaction in which a substance reacts with oxygen – the reaction is exothermic.
- 23. a chemical reaction in which a compound is made from its elements.
- 24. a form of local atmospheric pollution found in large cities in which several gases react with each other to produce harmful products.
- 25. a substance that can be used as a source of energy, usually by burning.
- 26. term that describes a solute that dissolves in a particular solvent.
- 27. the solid substance that has dissolved in a liquid to form a solution.
- 28. a molecule containing two atoms.
- 29. the liquid that dissolves the solid substance to form a solution.
- 30. the change of a vapor or a gas into liquid; during this process heat is given out to the surroundings.
- 31. a condition under which gas bubbles are able to form within a liquid – gas molecules escape from the body of a liquid, not just from its surface.
- 32. a substance, which cannot be further, divided into simpler substances by chemical methods; all the atoms of this substance contain the same number of protons.
- 33. the central, densest part of the Earth composed mainly of iron and nickel; the outer core is molten and surrounds the solid, inner core, which exists at very high temperature and pressure.
- 38. atoms of the same elements, which have different numbers of neutrons in their nuclei: they differ in their mass (nucleon) numbers.
- 40. is the smallest particle of an element that can take part in a chemical reaction.
- 41. the process of forming crystals from a saturated solution.
- 42. rain which has been made more acidic than normal by the presence of dissolved pollutants such as sulfur dioxide and nitrogen oxides.
- 45. a gas or a liquid, they are able to flow.
- 46. a subatomic particle with a relative mass of 1 and a charge of +1 found in the nucleus of all atoms.
Down
- 1. anything which occupies space and has mass.
- 2. the harmful effects on the air, water and soil of human activity and waste.
- 3. the chemical reaction (a combustion reaction) by which biological cells release the energy stored in glucose for the use by the cell or the body; the reaction is exothermic and produces carbon dioxide and water as the chemical by-products.
- 5. materials we get from the environment to meet our needs.
- 6. formed when a substance dissolves into another substance.
- 8. mixtures of elements (usually metals) designed to have the properties useful for a particular purpose.
- 11. the direct change of state from solid to gas or gas to solid: the liquid phase is bypassed.
- 12. the temperature at which a solid turns into a liquid – it has the same value as the freezing point.
- 13. the result of paper chromatography run, showing where the spots of the samples have moved to.
- 15. a mixture containing small particles of an insoluble solid, or droplets of an insoluble liquid, spread (suspended) throughout a liquid.
- 16. the process in by which solid different fluids mix as a result of the random motions of their particles.
- 19. element, which shows some of the properties of metals and some of Non – metals; for example, boron and silicon.
- 20. the system by which water circulates around the Earth, involving various changes of state in the process; the driving force behind the water cycle is energy from the Sun.
- 21. a type of chemical reaction where a compound breaks down into simpler substances.
- 22. a device for converting polluting exhaust gases from cars into less dangerous emissions.
- 24. the chemical process by which plants synthesize glucose from atmospheric carbon dioxide and water: the energy required for the process is captured from sunlight by chlorophyll molecules in the green leaves of the plant.
- 25. fuels such as coal, oil and natural gas, formed underground over geological periods of time from the remains of plants and animals.
- 34. a technique employed for the separation of mixtures of dissolved substances, which was originally used to separate colored dyes.
- 35. elements in Group 7 of the Periodic Table – generally the most reactive group of non – metals.
- 36. the system by which nitrogen and its compounds, both in the air and in the soil, are interchanged.
- 37. the combining power of an atom or group of atoms.
- 39. the process of boiling a liquid and then condensing the vapor produced back into the liquid: used to purify liquids and to separate liquids from solutions.
- 41. the solid, outermost, layer of the Earth; it is not continuous, but subdivided into plates of continental or oceanic layers.
- 43. charged particles made from an atom, or groups of atoms, by the loss or gain of electrons.
- 44. a black, solid fuel formed underground over geological periods of time by conditions of high pressure and temperature acting on decayed vegetation.