Mixtures, solutions, elements, compounds


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Mixtures, solutions, elements, compounds

  1. 1. 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
  2. 2. • 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
  3. 3. 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
  4. 4. • 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
  5. 5. • 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)
  6. 6. • To increase solubility you can change temperature, crush, stir, shake• Homogenous solutions– meaning the same• Heterogenous solutions– meaning different
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. • 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
  11. 11. • 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
  12. 12. 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
  13. 13. • 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
  14. 14. • 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)
  15. 15. • 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
  16. 16. • Common compounds• Salt, sugar, water