States of Matter


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This is a presentation to a primary PGCE group who are learning about teaching science to primary (ages 5 to 11) year olds in England.

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States of Matter

  1. 1. Primary PGCE science States of Matter and changes of state "The most exciting phrase to hear in science, the one that heralds the most discoveries, is not `Eureka!' but `That's funny ...' "
  2. 2. Programme of Study <ul><li>KS1 - Sc3: 2 Pupils should be taught to: </li></ul><ul><ul><li>Find out how the shapes of objects made from some materials can be changed by some processes, including squashing, bending, twisting and stretching </li></ul></ul><ul><ul><li>Explore and describe the way some everyday materials [for example, water, chocolate, bread, clay] change when they are heated or cooled. </li></ul></ul><ul><li>KS2 - Sc3:2 Pupils should be taught: </li></ul><ul><ul><li>To describe changes that occur when materials are mixed [for example, adding salt to water] </li></ul></ul><ul><ul><li>To describe changes that occur when materials [for example, water, clay, dough] are heated or cooled </li></ul></ul><ul><ul><li>That temperature is a measure of how hot or cold things are </li></ul></ul><ul><ul><li>About reversible changes, including dissolving, melting, boiling, condensing, freezing and evaporating </li></ul></ul><ul><ul><li>The part played by evaporation and condensation in the water cycle </li></ul></ul><ul><ul><li>That non-reversible changes [for example, vinegar reacting with bicarbonate of soda, plaster of Paris with water] result in the formation of new materials that may be useful </li></ul></ul><ul><ul><li>That burning materials [for example, wood, wax, natural gas] results in the formation of new materials and that this change is not usually reversible. </li></ul></ul><ul><li>Sc3:3 Pupils should be taught: </li></ul><ul><ul><li>How to separate solid particles of different sizes by sieving [for example, those in soil] </li></ul></ul><ul><ul><li>That some solids [for example, salt, sugar] dissolve in water to give solutions but some [for example, sand, chalk] do not </li></ul></ul><ul><ul><li>How to separate insoluble solids from liquids by filtering </li></ul></ul><ul><ul><li>How to recover dissolved solids by evaporating the liquid from the solutionTo use knowledge of solids, liquids and gases to decide how mixtures might be separated. </li></ul></ul>
  3. 3. States of Matter <ul><li>Kinetic Theory </li></ul><ul><li>Assumes all matter is made of PARTICLES </li></ul><ul><li>Particles are in constant motion (except at 0°K) </li></ul><ul><li>Particles are very small – may be atoms of an element; molecules; or a compound. </li></ul><ul><li>State depends on particle arrangement and particle motion </li></ul>
  4. 4. Solids <ul><li>Particles held together by strong forces of attraction – tightly packed, lattice-like structure </li></ul><ul><li>Movement of particles limited to vibration in a fixed position </li></ul><ul><li>Solids therefore DENSE, with FIXED SHAPE AND VOLUME </li></ul><ul><li>Visualise as: balls packed together in a box, for example </li></ul><ul><ul><li>What solids do you find in the home? </li></ul></ul>
  5. 5. Liquids I <ul><li>Weaker forces of attraction between particles, compared with a solid </li></ul><ul><li>More widely spaced, thus able to move more freely around each other </li></ul><ul><li>Liquids are less dense than solids </li></ul><ul><li>FIXED VOLUME but NOT a fixed shape (but if poured it will adopt the shape of the container’s base) </li></ul><ul><li>Visualise: balls in a ball pool </li></ul><ul><ul><li>What solids do you find in the home? </li></ul></ul>
  6. 6. Liquids II <ul><li>Particles in liquids are freer to move (as the bonds are looser) </li></ul><ul><li>Liquids have a definite volume and it is difficult to change this volume under PRESSURE. </li></ul><ul><li>The bonds between cause SURFACE TENSION at the surfaces of liquids </li></ul>
  7. 7. Gases <ul><li>Particles widely spaced </li></ul><ul><li>Move independently at HIGH SPEED (>500m/second) </li></ul><ul><li>Very low density – c.1000 times less dense than a liquid </li></ul><ul><li>No fixed volume or shape </li></ul><ul><li>Visualise: flying balls in National Lottery </li></ul>
  8. 8. Plasma <ul><li>Found at very high temperatures or high energies </li></ul><ul><li>Found in fluorescent light bulbs, plasma TVs, lightning strikes and in the sun! </li></ul><ul><li>Ionised gas – high energy strips electrons from atoms allowing ions and electrons to co-exist </li></ul><ul><li>Actually the most common state of matter in the universe </li></ul>
  9. 9. States of Matter
  10. 10. States of Matter – Poetry! Every thing in the world is one of these three: Either a solid (like a stone or a pea), Or a liquid (like water, or juice from a pear), Or a gas (like the oxygen found in the air).  You can hold solids in your hands and what’s more, They won’t ever drip on your clothes or the floor. Bigger or smaller you really can’t make them (except if you tear them or squash them or break them!). Next we have liquids, a quite different matter. They’re runny and drippy, they squirt and they splatter! To fit their container they can rearrange, But whatever happens, their volume won’t change.  Gases will spread out and try to escape Or fill their container and take on its shape You won’t often see them although you might stare – Most gases are see-through, like those in the air!
  11. 11. Changing States
  12. 12. The Water Cycle
  13. 13. Physical Changes <ul><li>Objects can be changed by physical forces. These include: </li></ul><ul><ul><li>Tearing (Shearing) </li></ul></ul><ul><ul><li>Cutting () </li></ul></ul><ul><ul><li>Pulling (Tension) </li></ul></ul><ul><ul><li>Heating </li></ul></ul><ul><ul><li>Squashing (Pressure) </li></ul></ul><ul><ul><li>Squeezing (Pressure) </li></ul></ul><ul><ul><li>Twisting (Torsion) </li></ul></ul><ul><li>A physical change does not alter the materials (substance) but can alter its shape or state it can usually (but not always) be reversed. </li></ul>
  14. 14. Chemical Changes <ul><li>The chemical property is the characteristic that gives a substance the ability to undergo a change that results in a new substance. </li></ul><ul><ul><li>Flammability </li></ul></ul><ul><ul><li>Reactivity </li></ul></ul><ul><li>Chemical changes are IRREVERSIBLE using physical means </li></ul><ul><li>Mass is never gained or lost in a CHEMICAL reaction – though it may be relocated </li></ul>
  15. 15. Indicators of chemical change <ul><li>There are a number of indicators that a chemical change may have taken place: </li></ul><ul><ul><li>Change of colour </li></ul></ul><ul><ul><li>Heat or light given off </li></ul></ul><ul><ul><li>Bubbles of gas given off </li></ul></ul><ul><ul><li>A precipitate (a solid formed in a liquid) </li></ul></ul><ul><ul><li>The change is difficult to reverse </li></ul></ul><ul><li>The fact that one of these has occurred is not proof of a chemical change but is an indication </li></ul>
  16. 16. Some everyday chemical changes <ul><li>Raw egg – Cooked Egg </li></ul><ul><li>Cake Mix – Cake </li></ul><ul><li>Paper – Ash </li></ul><ul><li>Steel - Rust </li></ul>
  17. 17. The Periodic Table
  18. 18. Elements, Compounds, Mixtures, Solutions, Suspensions and Colloids <ul><li>Element – A pure substance of only one kind of atom e.g. H 2 , Fe, S, Ag </li></ul><ul><li>Compound - two or more elements chemically combined – can sometimes be separated by chemical means e.g. Water (H 2 O), Sugar (C 12 H 22 O 11 ), Acetic Acid (Vinegar - CH 3 CO 2 H) or C 2 H 5 OH </li></ul><ul><li>Mixture - two or more elements or compounds physically combined. Can be separated using physical or mechanical means can be homogeneous (evenly spread) or heterogeneous (unevenly spread) </li></ul><ul><li>Solution - A homogeneous mixture in which one substance (the solute) is dissolved in another substance (the solvent). E.g: salt water (Water, the solvent, plus salt, the solute, produces the solution of salty water.) </li></ul><ul><li>Suspension - a heterogeneous mixture in which the particles are large enough to be seen by a microscope or the unaided eye (eventually, they settle out of the mixture). E.g: stirring a teaspoon of dirt in a glass of water </li></ul><ul><li>Colloid - a mixture where the size of particles in the mixture are between those of a solution and a suspension e.g. fog, cheese, butter, jellies, whipped cream </li></ul>
  19. 19. Elements
  20. 20. Questions?