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Three states of

There are three states of matter: ; and . They have different properties, which can be explained by looking at the arrangement of their .

SOLIDS contain particles arranged Liquids contain particles that roll Gases contain particles that move in a lattice structure. The particles around each other and settle on around very quickly. The particles vibrate in their fixed positions. the bottom of their container. travel in straight lines until they The particles are generally bounce off another or a This explains properties of solids: slightly further apart than in a surface. Gas particles are widely • They can’t be compressed solid. ( is an exception – spaced and tend to be only slightly (particles are already tightly particles are slightly further apart attracted to each other. packed together). than liquid water, which is why ice This explains properties of a gas: • They keep their shape and have floats.) • They fill available (slight a constant when they This explains properties of liquids: change container (particles are in attraction between particles). fixed positions). • They change shape when poured • They are very compressible into a different container (particles are widely spaced). (particles roll over each other and settle on the bottom). • They have constant volume (particles are close together). • They are slightly compressible. (There are slight between particles.)

Absolute zero This is the theoretical at which particles have the least amount of and the slowest movement. It occurs at -273.15 °C, or 0 on the scientific temperature scale. have not been able to cool down any substance to this temperature but have come very close. It used to be thought that particles would stop moving at but experiments have shown that this isn’t the case.

Particles in All particles are constantly in motion. This is called the kinetic theory of matter. When energy is added to particles (in the form of energy for example) they move faster. When energy is removed (for example by TERM CHANGE IN STATE cooling) then the particles move slower. melt () solid to liquid Changing state evaporate () liquid to gas condense () gas to liquid Adding or removing energy from particles can cause them to change state. Heating or cooling particles are freeze () liquid to solid ways of adding or taking away energy. It causes changes sublime (sublimation) solid to gas in the arrangement and movement of particles, and can to changes in state. There are names for the deposit (deposition) gas to solid changes.

ast0778 | Soft 3: Three states of matter (background sheet) developed for the Department of Education WA © The University of Western 2012 for conditions of use see spice.wa.edu.au/usage version 1.0 page 1 Licensed for NEALS A forms when a solid (the solute) dissolves A supersaturated solution forms when a solution in a liquid (the ). Although solutions are contains an amount of solute dissolved in the solvent generally thought of as a solid dissolved in a liquid, that is larger than the amount that is usually able both solute and solvent can be any : solid, liquid to dissolve in a saturated solution. This is tricky to or gas. In this case the solvent is the phase that occurs achieve and maintain but can be achieved by heating in the greatest quantity. the solute to a high temperature, adding the solvent to create a saturated solution, then either cooling the PHASES EXAMPLE SOLUTION solution; increasing the of the solution; or solid in liquid seawater removing some of the solvent through evaporation. Supersaturated solutions are usually very unstable. liquid in liquid in cleaners gas in liquid in water Separation techniques gas in gas air and solutions can be separated using solid in solid , physical methods. ( in ) TECHNIQUE APPLICATION Suspensions are a type of in which larger particles are held up or suspended by with chromatography separates substances that have the of the liquid or gas that contains them. different levels of attraction to Particles in a will eventually settle. In a a solvent (such as or ) the distributed crystallisation separates dissolved solids from particles are so small that they do not settle. liquids SUSPENSION COMPONENTS separates liquids dissolved in liquids ash suspended in air evaporation separate liquids from solids muddy water suspended in water that have very high melting water droplets points suspended in air separates suspended solids in liquid separates gas from liquids Solubility is the defined as of solute that can dissolve in a given amount of solvent, at a particular Particles temperature and pressure. Particles in states of matter may be in the form of When particles dissolve in a solvent to form a solution molecules or . they are surrounded by solvent particles, as shown in the learning object science 4: Solutions. A Molecules are particles that are made up of common misconception is that solute particles wander of one or more elements. They can be made up of around in the gaps between solvent particles. This is single atoms, for example and , or many not the case: there is an interaction between solute atoms like or carbon. Most molecules contain and solvent, known as , in which solvent atoms of different elements. For example, a water molecules form a that surrounds contains two atoms and one solvent molecules. If the solvent is water this is known oxygen ; and glucose contains six carbon atoms, as a hydration shell. twelve hydrogen atoms and six oxygen atoms in each molecule. Solutions have a saturation point. This is the point when no more solute can dissolve in the solvent and Ions are charged particles that have either gained the solution becomes a saturated solution. For some or lost . If they have gained electrons they solutes the saturation point varies widely, depending are negatively-charged particles and if they have on solvent temperature, for example sugar and water. lost electrons they are positively-charged particles. However other solutes show only a small increase in In common , chloride, each sodium atom solubility when temperature increases, for example loses one to form a sodium and salt. atoms each gain an electron to form chloride ions. More information The BBC Bitesize website has some useful activities. Type a topic (such as ‘distillation’) into the search box in the top right corner of the page at http://www.bbc.co.uk/schools/gcsebitesize/science.

ast0778 | Soft drink science 3: Three states of matter (background sheet) developed for the Department of Education WA © The University of Western Australia 2012 for conditions of use see spice.wa.edu.au/usage version 1.0 page 2