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chapter 2 matter

chapter 2 matter. 2.1 The Particulate Nature of Matter. the stuff of the universe is matter matter has mass and occupies space everything from you to the farthest places in the universe are made of just a small number of particles. The atomic nature of matter.

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chapter 2 matter

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  1. chapter 2matter

  2. 2.1 The Particulate Nature of Matter • the stuff of the universe is matter • matterhas mass and occupies space • everything from you to the farthest places in the universe are made of just a small number of particles

  3. The atomic nature of matter • we can see that the great variety of macroscopic things are composed of very similar microscopic bits • these tiny things are called atoms • we can actually now see individual atoms with special microscopes2

  4. even though things look uniform and continuous in the big world, they are made of individual atoms

  5. 2.2 Elements and Compounds • atoms look the same, they aren’t! • like letters, they can put together to make a million things • there are over 100 different types of atoms

  6. Compounds • Compounds: substances made by bonding atoms together in specific ways • are like words made of atomic letters • a single particle of a compound = molecule This is one molecule of water A drop of water made of millions and millions of molecules

  7. Elements • substances that contain only one type of atom are called elements • they can be single, or travel in pairs or more, but there is just one type of atom! • (remember: compounds have more than one!)

  8. here are three forms of the element carbon • notice: all have only one type of atom (C)

  9. Thinking cap time! • even though compounds have more than one type of atom they always have the same composition • e.g. water is always H2O • compounds have different properties than their elements • e.g. H2O is not like the hydrogen or oxygen elements from which it’s made

  10. 2.3 States of matter • there are three “earthly” states of matter • solid, liquid, and gas • to make it official:solid: rigid; fixed shape and volume

  11. liquid: definite volume that takes the shape of its container • gas: no fixed shape or volume; uniformly fills any container

  12. 2.4 Physical & Chemical Properties & Changes • physical properties help us ID things • include odor, color, volume, state, melting point, boiling point, density…

  13. Chemical properties describe how something can change into another • classic ex: burning, which takes a substance and changes it into something completely different giving off heat, light, and gases while it does • includes: rusting, digestion, growth (all change things into other things)

  14. an example

  15. Physical change usually involves just a change of state • same “stuff” when all is finished, just changed state • like the melting of water from fixed water molecules to freed up molecules • change? yes! something new? no!

  16. but! changing water into hydrogen and oxygen is a chemical change • new things were made that had different properties • called reaction • was water, now H2 and O2…

  17. Physical Change: Size Shape Phase Chemical Change: New substance Color change Temperature change Physical v. Chemical

  18. Phases of matter

  19. Summary

  20. 2.5 Mixtures and Pure Substances Mixtures • nearly everything around us is a mixture • Mixture = stuff with a variable composition • Ex. wood, soda, tap water, air

  21. air is a mixture of all these elements and cmpds • the amounts of each differ from place to place • !!!the composition of mixtures can vary, but the composition of compounds is always the same Which are elements? compounds?

  22. we’ve also seen metal mixtures called alloys • like rings and pipes and coins and England & France

  23. Pure substances • Pure substances are made of one thing only! • one set of properties • mixtures can be separated into pure subs

  24. Homogeneous and Heterogeneous mixtures • Homogeneous mixtures look the same(homos) throughout • called a Solution • like a solution of sugar water or salt water • or air or brass

  25. Heterogeneous mixtures don’t mix • you can see the different (heteros) things in there • like sand and water

  26. 2.6 Separation of Mixtures • so how do you separate all this crud? • use physical properties!!!

  27. this is a distillation apparatus • uses the property of boiling point to separate • is a physical separation (no change in substance)

  28. Filtration is another physical separation • not chemical!!!

  29. can use both (filter and distill) • but notice: all substances remain unchanged

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