Topic: Classifying Matter Indicate whether the following changes are physical or chemical. Burning wood Tearing paper Freezing Water Dissolving NaCl in H 2 O Mixing NaCl and SiO 2

Matter SubstancesMixtures Elements Compounds Heterogeneous Mixtures Homogeneous Mixtures Mixtures  Separated by physical methods Compounds  Separated by chemical methods Can it be separated by physical methods NOYES Atoms

Pure Substance uniform throughout Definite composition Same characteristic properties regardless of source which are pure substances

Element Substance that: cannot be broken down or decomposed into simpler substance only 1 kind of atom has definite properties Formulas have 1 uppercase letter Cu F F F F F F F F F2F2

Particle Diagrams             Atoms of a monatomic (1) element Molecules of a diatomic (2) element

I I N N O O F F Cl Br These seven elements are always diatomic H H H2H2 H2H2 N2N2 N2N2 O2O2 O2O2 F2F2 F2F2 Cl 2 Br 2 I2I2 I2I2

Element Song Big Bang Version sung by Sheldon

Compounds 2 or more different types of atoms chemically combined in a definite ratio differentProperties are different from those of elements formed from Only Broken into elements by chemical rxn Formulas have 2 or more uppercase letters H H H H H H O O H H H H Cl H H H H O O HCl H2OH2O

2Na + Cl 2  2NaCl Element or Compound? Na = element Cl 2 = element NaCl = compound

Particle Diagrams Atoms of a diatomic (2) compounds

Molecules: Can be elements or compounds – but must contain 2 or more total atoms (can be the same type or different) O O O O H H H H O O S S S S S S S S H H Cl S S S S S S S S O2O2 H2OH2O S8S8 HCl

Mixtures Combo of 2 or more pure substances (elements + elements) (elements + compounds) (compounds + compounds) notPhysically combined not chemically combined Each substance retains its own identity and properties

Mixtures Variable composition No unique properties (Think of sugar and salt mixed together) physical methodsSeparated by physical methods May be homogeneous or heterogeneous

Types of Mixtures Heterogeneous: NOT UNIFORM throughout -individual components visible - scatters light (can’t shine light through) Granite Oil in waterSalad dressing

Suspensions (type of heterogeneous mix.) Particles are larger can be evenly distributed by mechanical means (shaking the contents) Settle out on standing

Homogeneous (aka solutions): UNIFORM composition throughout- individual components not visible Solutions in gas & liquid phases transmit light (can shine light through) particles not big enough to scatter light look translucent

RECAP: Solution vs Suspension Solutions in gas & liquid phases transmit light particles not big enough to scatter light look translucent Suspensions look cloudy particles big enough to scatter light settle on standing

Solution(homogenous) vs Suspension(heterogeneous)

CuSO 4 (aq) Solution(homogenous) vs Suspension(heterogeneous)

K K O O H H K K K K K K K K O O O O O O K K H H O O H H H H O O H H H H O O H H H H O O H H H H O O H H H H O O H H H H O O H H H H O O H H O O F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- F-F- O O O O O O O O Homogenous Mixture: Compounds & elements Both in liquid phase Heterogeneous Mixture: elements & elements O 2 in the gas phase K in the solid phase Heterogeneous? Or Homogeneous? Compounds? Or Elements? Solid? Liquid? Gas?