U2L3 - Pure Substances and Mixtures

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Science Fusion PowerNotes - Grade 8
Unit 2 Lesson 3 - Pure Substances and Mixtures

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U2L3 - Pure Substances and Mixtures

  1. 1. Unit 2 Lesson 3 Pure Substances and Mixtures Copyright © Houghton Mifflin Harcourt Publishing Company
  2. 2. Unit 2 Lesson 3 Pure Substances and Mixtures Indiana Standards Copyright © Houghton Mifflin Harcourt Publishing Company • 8.1.1 Explain that all matter is composed of particular arrangements of atoms of approximately one hundred elements.. • 8.1.5 Explain that atoms join together to form molecules and compounds and illustrate with diagrams the relationship between atoms and compounds and/or molecules.
  3. 3. Unit 2 Lesson 3 Pure Substances and Mixtures Indiana Standards Copyright © Houghton Mifflin Harcourt Publishing Company • 8.1.6 Explain that elements and compounds have characteristic properties such as density, boiling points and melting points, that remain unchanged regardless of the sample size.
  4. 4. A Great Combination Copyright © Houghton Mifflin Harcourt Publishing Company How can matter be classified? • Matter is made up of basic “ingredients” known as atoms. • An atom is the smallest unit of an element that maintains the properties of that element. • Substances are classified as elements, compounds, and mixtures. Unit 2 Lesson 3 Pure Substances and Mixtures
  5. 5. How can matter be classified? • An element is made of only one kind of atom. • A compound is made up of different kinds of atoms chemically combined. • A mixture contains a variety of elements and compounds that are not chemically combined. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  6. 6. How can matter be classified? • Is water an element, compound, or mixture? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  7. 7. Pure Genius Copyright © Houghton Mifflin Harcourt Publishing Company What are pure substances? • A pure substance is a substance with definite physical and chemical properties. • Pure substances are made up of just one type of particle. • Elements and compounds are pure substances. Unit 2 Lesson 3 Pure Substances and Mixtures
  8. 8. What are pure substances? • Physical changes such as melting, freezing, cutting, or smashing do not change the identity of pure substances. • When a pure substance undergoes a chemical change, it is no longer that same substance. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  9. 9. Classified Information Copyright © Houghton Mifflin Harcourt Publishing Company How can elements be classified? • Elements are classified as metals, nonmetals, or metalloids. • Classifying elements helps scientists predict the properties of elements. • The periodic table is a tool used to classify and identify elements that have similar properties. Unit 2 Lesson 3 Pure Substances and Mixtures
  10. 10. How can compounds be classified? • Compounds can be classified as acidic, basic, or neutral by measuring pH. • Pure water has a pH of 7. Acids have a pH below 7. Bases have a pH above 7. • Blue litmus paper turns red in the presence of an acid. • Red litmus paper turns blue in the presence of a base. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  11. 11. How can compounds be classified? • Compounds can be organic or inorganic. • Organic compounds are those that contain carbon and hydrogen. • Organic compounds made by living things are called biochemicals. • Carbohydrates, lipids, proteins, and nucleic acids are biochemical compounds. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  12. 12. Mix and Match Copyright © Houghton Mifflin Harcourt Publishing Company What are mixtures? • A mixture is a combination of two or more substances that are combined physically but not chemically. • Mixtures are not pure substances and do not have definite properties. Unit 2 Lesson 3 Pure Substances and Mixtures
  13. 13. What are mixtures? • Substances within a mixture keep their identities and individual properties. • Mixtures can be separated by physical changes, although some mixtures are difficult to separate. • Magnets, centrifuges, filters, and other materials can be used to separate mixtures. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  14. 14. Simple Solution Copyright © Houghton Mifflin Harcourt Publishing Company How can mixtures be classified? • A heterogeneous mixture is one that does not have a uniform composition. • A homogeneous mixture has the same composition throughout. Unit 2 Lesson 3 Pure Substances and Mixtures
  15. 15. How can mixtures be classified? • A suspension is a heterogeneous mixture. • Particles in a suspension are spread throughout a liquid or gas, but are too large to stay mixed unless shaken or stirred. • Particles settle in suspensions. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures
  16. 16. How can mixtures be classified? • A solution is a homogeneous mixture in which one substance is dissolved in another substance. • Colloids have particles that are unevenly spread throughout the mixture. • Unlike a suspension, particles in colloids are too small to settle out of the mixture. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 3 Pure Substances and Mixtures

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