Substances and Mixtures!

1. Substances and Mixtures!

2. Substances: • Matter– everythingthat has mass and takes up space. • It can be classifiedbyitsphysicalproperties. • Onewaytoclassifymatterisbasedonitschemicalcomposition. • Matterthat has thesamecomposition and propertiesthroughtoutiscalleda substance. • There are twotypesof substances–elements and compounds.

3. Substances: • Rememberthatelements are substancesmade up of onlyonetype of atom. • Differentelements can combine toform new substancescalledcompounds. • Compounds are twoor more elementsthat are chemicallybondedtogether.

4. Substances: • Compounds can be brokendownonlybychemicalmeans in totheelementsthatcombinedtomakethem. • Forexample, boiling, freezing, stirringorfilteringwillnotseparatethehydrogenatomsfromtheoxygenatoms of water. • However, ifelectricityisaddedtowater, it can be brokendownintohydrogen gas and oxygen gas.

5. Mixtures: • Whentwoor more substances come togetherbutdon’tchemically combine or bond tomake a new substance, a mixtureresults. • Unlikecompounds, theproportions of thesubstances in a mixture can be changedwithoutchangingtheidentity of the mixture. • Forexample, ifyouputsomesandinto a bucket of water, thesanddoesn’tchemically combine withthesand and water.

6. Mixtures: • Physicalproperties can be usedtoseparate mixtures intosimplersubstances. • Thesolidsand can be filteredfromtheliquidwaterusing a sieve.

7. Homogeneous Mixtures: • Homogeneousmeans ¨thesamethroughout.¨ • Homogeneous mixtures contain more thanonesubstanceevenlymixedbutnotchemicallybondedtogether. • Youcan’tseethedifferentparts in a homogeneous mixture no matterhowcloselyyou look.

8. Homogeneous Mixtures: • Homogeneous mixtures can be solid, liquid, or gas. • Thebrass in a trumpetis a solid mixture of zinc and copper–twoelements. • Sugarwateris a homogeneousliquid mixture of water and sugar–bothcompounds. • Air is a homogeneous mixture of elements: nitrogen, oxygen, argon, neon, and helium–and twocompounds:carbondioxide and water. • Homogeneous mixture isalsoknown as a solution.

9. Whatisthedifferencebetween a substance and a homogeneous mixture? • The difference between a homogeneous mixture and a pure substance is that a pure substance has a fixed composition and cannot be separated because it is chemically bonded and a homogeneous mixture can be separated.

10. Heterogeneous Mixtures: • A hererogeneous mixture isone of twoor more substancesthat are notmixedevenly. • You can seethedifferentparts of a heterogeneous mixture, such as a mixture of sand and water. • A pizza is a heterogeneous mixture. • Otherexamplesincludesalad, a bookshelf full of books, or a toolbox full of nuts, bolts, screws, nails, and tools (etc.).

11. Questions… • Whatisthedifferencebetween a homogeneous and a heterogeneous mixture? • How are substancesdifferentfromhomogeneous mixtures?

12. Theend!