Mixture

• Two or more substances that are not chemically combined

• All mixtures can be physically separated• Ways to separate mixtures

– Distillation-use boiling point– Magnet-uses magnetism– Centrifuge-use density– Filtering-separates large particles from

smaller ones

• Ratio of mixtures are not fixed• Substances keep their identities• Mixtures can be solid, liquid or gas• Examples of mixtures

– Chex mix– Raisin bran– Pizza– Mixed nuts– air

Solutions

• Mixture that appears to be a single substance

• Material is evenly distributed by dissolving

• Material must be soluble (able to dissolve)

• Solute is what is dissolved

• Solvent what the solute is dissolved in

• Water is the universal solvent

• Materials that will not dissolve (insoluble) forms a mixture that is not a solution

• Examples of solutions– Sodas– Gasoline– Ice tea– Salt water– Kool aid

• In solutions the particles are so small they never settle out (sink to bottom), can’t scatter light nor can they be filtered

• Solubility is the ability of substances to dissolve at a given temperature and pressure

• How much of a solute a solvent can hold is the concentration (grams of solute/milliliter of solvent, g/mL)

• To increase solubility you can change temperature, crush, stir, shake

• Homogenous solutions– meaning the same

• Heterogenous solutions– meaning different

Suspensions

• Suspensions are mixtures where the particles are heavy enough to settle out (sink to bottom) of the solution, scatter light, can be filtered

• Examples of suspensions– Snow globe– Italian dressing

Colloids

• Colloids are mixtures where the particles are evenly dispersed but are not heavy enough to settle out, can scatter light, can’t be filtered

• Examples of colloids– Mayo– Whip cream– pudding

Elements

• elements are pure substance that can not be separated into simpler substances by physical or chemical means

• Pure substance is a substance with only one type of particle called atoms

• All atoms of an element are identical regardless of how much you have

• Elements can be identified by their characteristic properties

• The properties, both chemical and physical do not depend on the amount of the element present

• Elements can have similar properties but each element has some property that makes it unique

• Elements are classified by categories

• Metals – shiny, good conductors

• Nonmetals – dull, poor conductors

• Metalloids –has properties of metals and nonmetals depending on conditions

• Categories allow unknown elements to be placed in the periodic table based on similar properties

Compounds

• Pure substance composed of two or more elements that are chemically combined

• Compounds are formed by elements reacting or having a chemical change

• A particle of a compound is a molecule• Elements do not form compounds

randomly• All compounds are formed from only the

elements on the periodic table

• Compounds form in specific mass ratio

• Ex: mass of hydrogen to mass oxygen in water is hydrogen 1 to oxygen 8 which can be written as 1:8. For every molecule of water, the ratio is the same, if the ratio is different, then the compound can not be water

• When elements form compounds, new characteristics properties are created

• Compounds have properties that differ from the elements that formed them

• Na (sodium) reactive alkali metal + Cl (chlorine) poisonous gas → NaCl (table salt)

• Some compounds can be broken down into their elements by a chemical change

• Other compounds break down into simpler compounds instead of elements

• The only way to separate a compound into elements or other compounds is by a chemical reaction which allows for a chemical change

• Two ways: is to apply energy or electric current

• Common compounds

• Salt, sugar, water