Unit 1 Lesson 4 Pure Substances and Mixtures Copyright © Houghton Mifflin Harcourt Publishing Company

A Great Combination How can matter be classified? Unit 1 Lesson 4 Pure Substances and Mixtures A Great Combination 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. Copyright © Houghton Mifflin Harcourt Publishing Company 2

How can matter be classified? Unit 1 Lesson 4 Pure Substances and Mixtures How can matter be classified? An element is made of only one kind of atom. Example: Gold is made of only gold atoms, oxygen is made of only oxygen atoms. A compound is a molecule that is made up of different kinds of atoms that are chemically combined. Example: Water (H₂O) is a molecule made of Hydrogen and Oxygen atoms that are combined chemically. A mixture contains a variety of elements and compounds that are not chemically combined. Example: Salt water is a mixture of salt (NaCl) and water (H₂O) but are NOT chemically combined. Copyright © Houghton Mifflin Harcourt Publishing Company 3

H H O How can matter be classified? Unit 1 Lesson 4 Pure Substances and Mixtures How can matter be classified? Is water an element, a compound, or a mixture? H H O Copyright © Houghton Mifflin Harcourt Publishing Company 4

Pure Genius What are pure substances? Unit 1 Lesson 4 Pure Substances and Mixtures Pure Genius 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 element or molecule. Elements and compounds are pure substances. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What are pure substances? Unit 1 Lesson 4 Pure Substances and Mixtures What are pure substances? Physical changes such as melting, freezing, cutting, or smashing do not change the identity of pure substances. Example: Water can be boiled into a gas and frozen into a solid, but will always be water. Example: Iron can be cut, bent and melted, but will always be iron When a pure substance undergoes a chemical change, it is no longer that same substance. Example: Water can be separated into its original elements (Hydrogen, Oxygen) using a chemical process called electrolysis. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Water

Classified Information Unit 1 Lesson 4 Pure Substances and Mixtures Classified Information 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. Copyright © Houghton Mifflin Harcourt Publishing Company 8

How can compounds be classified? Unit 1 Lesson 4 Pure Substances and Mixtures 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 9

P pH Scale & Examples

How can compounds be classified? Unit 1 Lesson 4 Pure Substances and Mixtures How can compounds be classified? Compounds can be organic or inorganic. Organic compounds are those that contain a combination of 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 11

Organic Compounds: CH4 - methane C3H8 - propane C4H10 - butane C6H6 - benzene C6H₁₀O₅ – starch (C6H10O5) C6H10O5 – cellulose C₁₂H₂₂O₁₁ – sugar Inorganic Compounds: NaCl - sodium chloride CO2 - carbon dioxide H2O - water HCl - hydrochloric acid CuCl2 - copper chloride Fe2O3 - iron oxide MgCl2 - magnesium chloride

Mix and Match What are mixtures? Unit 1 Lesson 4 Pure Substances and Mixtures Mix and Match 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. The properties of a mixture can change depending on the amount of each material being mixed. Copyright © Houghton Mifflin Harcourt Publishing Company 13

Unit 1 Lesson 4 Pure Substances and Mixtures 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 14

Simple Solution How can mixtures be classified? Unit 1 Lesson 4 Pure Substances and Mixtures Simple Solution 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. Copyright © Houghton Mifflin Harcourt Publishing Company 15

Heterogeneous Mixtures

Heterogeneous Mixtures Unit 1 Lesson 4 Pure Substances and Mixtures Heterogeneous Mixtures 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 17

Suspensions

Unit 1 Lesson 4 Pure Substances and Mixtures Homogenous Mixtures 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 19

Solutions

Colloids