Term | Definition |
Matter | Anything that occupies space and has mass. |
Element | A substance that consists only one type of atom. |
Compound | A substance that contains two or more elements that are chemically bonded together. |
Molecule | A group of two or more atoms. |
Ion | A positively-charged or negatively-charged particle. |
Solid | Particles are packed closely together in an orderly manner.Particles can only vibrate at their fixed position.Strong forces between the particles.Low energy content because movement is restricted. |
Liquid | Particles are packed closely but not in an orderly arrangement.Particles can vibrate,move and rotate.They collide against each other.Strong forces but weaker than solid.High energy content because particles can move freely. |
Gas | Particles are very far apart and in an random arrangement.The collision is greater than liquid.Weak force between the particles.Highest energy content because movement is random. |
SLS | Heat energy is absorbed. |
Heating of Naphthalene | Temperature remains constant because the heat energy absorbed by the particles is used to overcome the forces between particles so that solid can turn into liquid. |
Cooling of Naphthalene | Temperature remains constant because the heat loss to the surroundings is balanced by the heat energy as the particles attract one another to form solid. |
During heating of naphthalene, | Placed in the conical flask because to ensure even heating and because naphthalene is flammable.Is stirred continuously to ensure even heating. |
During cooling of naphthalene, | Is placed into a conical flask because to ensure even cooling process to minimise the heat loss to the surroundings.Is stirred continuously to avoid supercooling. |
Supercooling | is a condition in which the temperature of a cooling liquid drops below its normal freezing point without the appearance of a solid. |
John Dalton | Atom |
J.J.Thomson | Electron |
Ernest Rutherford | Proton |
Niels Bohr | Atomic model based on the Solar System |
James Chadwick | Nuetrons |
Proton number | number of protons and electrons |
Nucleon number | proton number + neutrons number |
Neutrons number | nucleon number - proton number |
Isotopes | are atoms of the same element with the same number of protons but different number of neutrons. |
Uses of isotopes | Medical uses,Agriculture,Power sources,Archaeological and Industry. |
Medical uses | Cobalt-60-Gamma Rays are used in radioptherapy for the treatment of cancer.Iodine-131 is used in the treatment of thyroid diseases. |
Power sources | Uranium-235 is the fuel used in nuclear power stations. |
Agriculture | Phosphorus-32 for fertilisers.Carbon-14 to study of photosynthesis. |
Archaeological | Carbon-14 used to estimate the ages of artifacts like bones. |
Industry | Sodium-24 used to trace leakage of pipes.Cobalt-60 to destroy bacteria in food.Krypton-85 to control the thickness of plastic. |