An Atom (Neil Bohr model All matter is made up of atoms and molecules A nucleon is any particle existing in the nucleus These atoms or molecules contain protons, electrons and neutrons Usually the atom is neutral but if the is an excess of protons (positively charged) or electrons (negatively charged) it is an ion… Cation – positively charged atom Anion – negatively charged atom An Atom (Neil Bohr model Sub-atomic particle Relative mass Relative charge Location in the atom Proton 1 a.m.u. +1 In the nucleus Neuton Electron 1/1840 a.m.u. -1 Elementary charge of 1.60 x 10-19 C Outside the nucleus

The three basic states of matter are Solids Liquids and Gases (for your personal knowledge know there are also Bose-Einstein Condensates Plasmas

PHYSICAL PROPERTY OF MATTER DETAIL Colour Size Shape Elasticity Is the ability of the material t return to its original shape and size after it has been bent, stretched or compressed by a deforming force Strength Ability of a material to support a heavy load without breaking or tearing Hardness Ability of a material to withstand scratches and wear. The hardness can be determined by scratching it with certain solids... it uses a comparison scale called the Mohs scale (diamond is 10 a fingernail is 2.5) Solubility Of a substance in a solvent (usually liquid) is the maximum quantity of that substance which can dissolve in a given quantity of the solvent at that temperature. The solubility varies with temperature. ( the substance that dissolves is called the solute, the substance that does the dissolving is called the solvent, the solvent and the solute together make the solution) Density is the mass per unit volume of a material. It is a measure of how light or heavy the object is. It can help determine if an object may sink or float in another material. Its unit is kg/m3 or g/cm3 Melting point The temperature at which the substance changes from solid to liquid. Freezing point is the temperature at which the substance changes from liquid to solid Electrical conductivity A measure of how readily electricity flows through the substance. Substances that allow electricity to easily flow through them are called electrical conductors; insulators do not allow electricity to flow through them easily. Eg. Metals are good conductors, non-metals are usually insulators. Heat conductivity A measure of how readily heat flows through the substance. Substances that allow heat to flow through them easily are called heat conductors eg. Metals (why?), heat insulators are those that do not allow heat to flow through them easily, eg. Non metals such as wood and plastics.

Temperature Is a property of an object which determines the direction of net heat flow when an object is placed in contact with some other object. It is a measure of the Hotness or Coldness of the material Whereas Heat is a form of energy

On a molecular level the temperature of a body is a measure of the average kinetic energies of the molecules of the body

A change in temperature can cause certain physical properties of substances to vary: Volume of a liquid or gas E.m.f. between the ends of two different wires joined Electrical resistance of a metal The pressure of a constant volume of gas

Instruments used to measure temperature change: Thermometers: Laboratory thermometers: mercury in glass, alcohol in glass Clinical thermometers Thermocouples

The centigrade scale/the Celsius scale In order to express temperatures a scale and a unit of temperature was used and defined temperatures of: - 0°C lower fixed limit and 100°C upper fixed limit (the 100 equal parts is the fundamental interval)

The Kelvin For measurements and calculations in Science we convert °C to Kelvin: + 273 to the °C value

Theories of heat Caloric theory: -heat was considered to be an invisible fluid called caloric -temperature changes in a body was due to the addition or removal of caloric -temperature was directly dependant on the amount of caloric it contained - Supported by experiments involving mixture of 2 materials at different temperatures that become same temperature

Theories of heat Caloric theory failed in that -a material did not necessarily gain weight if it gained temperature 2 bodies supplied with the same amount of heat do not reach same temperature Addition of heat does not produce a temperature rise (melting, boiling) Friction generates heat…where was this coming from?

The kinetic theory seemed to have the answers: Rumford observed that heat was produced by friction in canon boring due to the work being done by horses which powered the boring machines The kinetic theory explains that the heat content of a body is the sum of the kinetic energy of the individual particles of matter contained in a body Heat is a form of energy measured in Joules (name given by scientist who proved using experiments)

Three major methods of heat transfer in materials Conduction – mostly in solids Convection – mostly in fluids Radiation – mostly in a vacuum or gases

Convection By the variation of density of the material a convection current is set up such that the less dense fluid rises and the more dense fluid sinks to below

Radiation Transfer of heat energy via electromagnetic waves because the energy travels in a combination of electric and magnetic waves. This energy is released when these waves are absorbed by an object. For example, energy traveling from the sun to your skin, you can feel your skin getting warmer as energy is absorbed.