1446867
| Pregunta | Respuesta |
| Describe the particles in a solid. (e.g. spacing, arrangement, movement and forces) | Close together and touching one another Regular, repeating pattern Vibrate about a fixed position, but do not move apart The force between particles in stronger than in a liquid or gas |
| Describe the particles in a liquid. (e.g. spacing, arrangement, movement and forces) | Close together and touching one another Irregular arrangement Move around and slide past one another Forces are not as strong as in a solid, but stronger than in a gas |
| Describe the particles in a gas. (e.g. spacing, arrangement, movement and forces) | Spaced far apart An irregular arrangement Move freely and constantly collide with one another Non-existent forces between particles |
| What is the change called when: * a solid changes to a liquid? *a liquid changes to a solid? *a liquid changes to a gas? *a gas changes to a liquid? *a solid changes to a gas? | * solid-liquid = Melting *liquid-solid = Freezing *liquid - gas = Boiling/evaporating *gas - liquid = Condensing *solid - gas = Subliming |
| Explain, in terms of particles, the change between a liquid to a gas. | The particles gain kinetic energy and move further apart. Eventually the forces of attraction between the particles are completely broken and they are able to escape from the liquid. |
| Explain, in terms of particles, the change between a liquid to a solid. | The particles lose kinetic energy and this allows the forces of attraction between the particles to hold them together. The particles arrange themselves into a regular pattern are no longer able to slide past one another. |
| Give two pieces of evidence to support the particle theory. | *Dilution of coloured solutions - Potassium Manganate crystals are dissolved in water a purple solution is formed- large number of particles in small amount of solid *Diffusion- Bromine from one flask to another- particles in gas easily mix together |
| What is an atom? | Smallest particle of an element that can take place in a chemical reaction |
| What is an element? | A substance made up of atoms which all contain the same number of protons. |
| What is a compound? | A substance made up of two or more elements chemically combined together. |
| What is a mixture? | A combination of two or more substances that are not chemically joined together. |
| What is a molecule? | The smallest particle that can have a separate, independent existence. |
| When should you carry out filtration? | To separate an undissolved solid from a mixture of the solid and a liquid/solution (e.g. sand from a mixture of sand and water) |
| When should you carry out evaporation? | To separate a dissolved solid from a solution, when the solid has similar solubilities in both hot and cold solvent (e.g. sodium chloride from a solution of sodium chloride in water) |
| When should you carry out crystallisation? | To separate a dissolved solid from a solution, when the solid is much more soluble in hot solvent than in cold (e.g. copper sulphate from a solution of copper sulphate in water) |
| When should you carry out simple distillation? | To separate a liquid from a solution (e.g. water from a solution of sodium chloride in water) |
| When should you carry out fractional distillation? | To separate two or more liquids that are miscible with one another (e.g. ethanol and water from a mixture of the two) |
| What are miscible liquids? | Liquids which will mix together. |
| When should you carry out paper chromatography? | To separate substances that have different solubilities in a given solvent (e.g. different coloured inks that have been mixed together to make black ink) |
| What is thermal decomposition? | Breaking down by using heat |
| What is electrolysis? | The decomposition of a substance by passing an electric current through it |
| What is an atom made up of? | Proton Electron Neutron |
| Relative charge, relative mass and position of the three sub-atomic particles | Neutron- charge 0, mass 1, nucleus Proton- charge 1, mass 1, nucleus Electron- charge -1, mass 0, electron shells |
| What is the atomic number? | Number of protons in the nucleus of an atom of an element |
| What is the mass number? | Number of protons + number of neutrons in the nucleus of an atom of an element |
| What is the top number showed by the element in the periodic table? | Mass number |
| What are isotopes? | Atoms that have the same atomic number (same number of protons) but different mass numbers (different number of neutrons) |
| Electrons exist ............. the nucleus of atoms in different ................ ....................... called ................. .................... . There are several .................. ....................... . | around energy levels electron shells electron shells |
| What is Ar? | Relative atomic mass (Mean mass of all the isotopes of a particular element) |
| What is Mr? | Relative formula mass- The sum of all the relative atomic masses of all the atoms present in the formula of a substance. |
| What is a mole? | 1 mole is the amount of substance that contains 6 x 10^23 particles (atoms, molecules or formulae) of the substance. |
| How do you calculate the mass of 1 mole? | the relative atomic mass (Ar) expressed in grams |
| How do you calculate the mass of a substance (in grams) from the amount (number of moles)? | amount of moles x Mr |
| How do you calculate the amount in moles from the mass of the substance? | Mass of substance (grams) / Mr |
| What is the molar volume? | One mole of any gas has a volume of 24dm^3 at room temperature and pressure. |
| How to work out the volume of gas (in dm^3 and cm^3) from the amount of gas? | Volume in dm^3 = amount x 24 Volume in cm^3 = amount x 24 000 |
| How to work out the amount of gas (in moles) from the volume of gas in a) dm^3 b) cm^3 | a) volume (in dm^3) / 24 b) volume (in cm^3) /24 000 |
| What is the empirical formula? | The simplist whole number ratio |
| How do you work out the empirical formula? (e.g. percentage composition: aluminium = 52.94 %; oxygen = 47.06 % empirical formula of Aluminium Oxide?) | Divide by Ar (Al= 52.94 / 27=1.96 O= 47.06 / 16=2.94) Divide by smallest to find ratio (Al =1.96/1.96 = 1 O=2.94 / 1.96 = 1.5) 2:3 Al2O3 |
| What is the molecular formula? | The exact number of atoms |
| How do you work out the amount of dissolved substance (in moles) using the concentration? | [volume of solution (in cm^3) x concentration of solution (in mol/dm^3)] / 1000 |
| What is the theoretical yield? | The maximum amount of a product that could be formed from a given amount of a reactant |
| How do you calculate a percentage yield? | (Yield obtained / theoretical yield) / 100 |
| What is an ion? How are ions formed? | An electrically charged atom or group of atoms By the loss or gain of electrons |
| What things make ionic compounds? What is an ionic bond? | atoms of metals and atoms of non-metals Electrostatic force of attraction between oppositely charged ions (e.g. transferred electrons) |
| There are no ..................... in ionic compounds. | Molecules |
| Why do ionic compounds have a high melting and boiling point? | Electrostatic forces are strong and there is many of them to break in an ionic crystal. Therefore a large amount of energy is required to overcome the forces. |
| When are covalent bonds formed? What is a covalent bond? | Between atoms of non-metallic elements The force of attraction between the nuclei of two atoms and a pair of electrons shared between them |
| Simple molecular substance have .......... melting and boiling points because the forces of attraction between the molecules are ....... and therefore ........... energy is required to overcome them. | low weak little |
| Give 2 examples of giant covalent structures made from carbon. Describe the bonding in them. Describe the forces in them. | Diamond - Each carbon atom forms four single covalent bonds. 3D structure formed. Covalent bonds are strong. No weak forces in the structure. Graphite - Each carbon atoms forms 3 single covalent bonds. Layered structure formed. Covalent bonds- strong. Forces of attraction between layers -weak |
| Describe the uses and properties of diamond. | Very high melting point Very hard and abrasive Does not conduct electricity Cutting tools Jewellery |
| Describe the properties and uses of graphite. | Very high melting point. Soft and slippery. Conducts electricity. Lubricant Electrodes for electrolysis |
| Describe the structure of metals. Properties of metals | Giant, 3D lattice structure of positive ions in a sea of delocalised valence electrons High melting and boiling points Good conductors of electricity Malleable and ductile |
| What are the conditions of electrolysis? What is the electrolyte? | Ionic compounds when molten or an aqueous solution Substance being electrolysed |
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