Mixtures ,Elements & Compounds Describing Matter Mixtures ,Elements & Compounds

Mixtures, Elements, Compounds Scientists like to classify things. One way that scientists classify matter is by its composition (What it is made up of). Ultimately, all matter can be classified as mixtures, elements and compounds. Salad Gold Salt (NaCl)

Why isn’t it a good idea to classify matter by its phases Why isn’t it a good idea to classify matter by its phases? (solid, Liquid, Gas) Because one kind of substance can exist in more than one phase – such as H20. And matter changes phases rather easily.

Why isn’t matter classified according to its physical characteristics, such as color? Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.

To identify a mixture scientists ask themselves……. Is the matter uniform throughout? Can it be separated by physical means? Can it be separated by chemical means? C12H22O11 Jellybeans

Mixtures: a blend of at least 2 substances. They can be either; Heterogenoues-not uniform Homogenoues-uniform Chocolate chip cookies Soil Gravel Kool aid Salt Air water

Can it be separated by physical means? If the answer is yes, the matter is a homogeneous mixture or solution. If the answer is no its an element or a compound Homogenoues Mixtures (solutions)

Solutions are homogenous mixtures Air is a solution of oxygen and other gases dissolved in nitrogen

Examples of heterogeneoues mixtures Sand and pebbles Oil and water Granite Considered the “least mixed.” Does not appear to be the same throughout. Particles are large enough to be seen. Can be separated from the mixture.

AIR IS A SOLUTION A homogeneous mixture in which there is both a solute and solvent present is also a solution.

Ocean water is a solution Salt is dissolved (solute) into water (solvent)

Metals dissolved in metals are called alloys. Types of solutions The substance that is dissolved is the solute and the substance that does the dissolving is the solvent. Example Solute Solvent Gas Air (oxygen in nitrogen) Liquid Soda water (Co2 in H20) Solid Ocean water (salt in water) Solid Gold jewelry (copper in gold) Metals dissolved in metals are called alloys.

Alloys Stainless steel is a mixture of iron and chromium. Brass is an alloy of copper and zinc.

The universal solvent: Water

Colloids In a colloid the particles are mixed together but not dissolved. The particles are relatively large and are kept suspended.

Separation of a Mixture Components of dyes such as ink may be separated by paper chromatography.

Separation of a Mixture Distillation: takes advantage of different boiling points. NaCl boils at 1415 oC

Separation of a Mixture Iron filings and sulfur (use magnet) Evaporation and Filtration

Classification of Matter

ELEMENTS

Can it be separated by physical means Can it be separated by physical means? If the answer is no, the matter is a pure substance. An Element A Compound All elements are made of atoms. Atoms of the same element are alike. Atoms of different elements are different Compounds are also pure substances. --made from more than one element. Water is a compound. Water can be broken down into simpler substances – hydrogen and oxygen.

Common Elements Aluminum Al Bromine Br Calcium Ca Carbon C Gold Au Helium He Hydrogen H Nitrogen N

Compound vs. Mixture Compound Mixture Made of one kind of material Made of more than one kind of material Made by a chemical change physical change Definite composition Variable

Which is it? Compound Mixture Element

Element, Compound, or Mixture? Rocks

Element, Compound, or Mixture? Rocks

Element, Compound, or Mixture? Copper

Element, Compound, or Mixture? Copper Cu

Element, Compound, or Mixture? Jelly Beans

Element, Compound, or Mixture? Jelly Beans

Element, Compound, or Mixture? Table Sugar

Element, Compound, or Mixture? Table Sugar C12H22O11

Element, Compound, or Mixture? Diamond

Element, Compound, or Mixture? Diamond C

Element, Compound, or Mixture? Tea

Element, Compound, or Mixture? Tea

Element, Compound, or Mixture? Salt

Element, Compound, or Mixture? NaCl Salt

Element, Compound, or Mixture? Neon Gas

Element, Compound, or Mixture? Ne Neon Gas

Element, Compound, or Mixture? Salad

Element, Compound, or Mixture? Salad

Element, Compound, or Mixture? Pure Water

Element, Compound, or Mixture? Pure Water H2O

Element, Compound, or Mixture? Aluminum

Element, Compound, or Mixture? Aluminum Al

Element, Compound, or Mixture? Lemonade

Element, Compound, or Mixture? Lemonade

Element, Compound, or Mixture? Silver

Element, Compound, or Mixture? Silver Ag

Element, Compound, or Mixture? Sand

Element, Compound, or Mixture? Sand