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Matter

Matter. Things You Need in Your N otes:. Terms: matter, element, atom, molecule, compound, pure substance, mixture, homogeneous & heterogeneous mixture, miscible Answers to the following questions: How can matter be classified? Why are carbon and copper classified as elements?

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Matter

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  1. Matter

  2. Things You Need in Your Notes: • Terms: matter, element, atom, molecule, compound, pure substance, mixture, homogeneous & heterogeneous mixture, miscible • Answers to the following questions: • How can matter be classified? • Why are carbon and copper classified as elements? • How are elements related to compounds? • What is the difference between a pure substance and a mixture? (I will do a binder check the day before a test for a quiz grade)

  3. What is matter? • Matter = anything that has mass & takes up space. • Chemists look at makeup, properties, changes, and interactions of matter • Matter can be classified into three types: an element, a compound, or a mixture.

  4. Elements • Element = a substance that cannot be separated or broken down into simpler substances by chemical means. • Ex: Carbon cannot be broken down any further by normal chemical processes • Atom = smallest unit of an element that maintains its chemical properties • Every element is made of 1 type of atom • Carbon has many forms: diamond, graphite, etc. • Copper no matter its appearance is always made of copper atoms

  5. Elements are represented by symbols • Each element is represented by 1 or 2 letters that are used worldwide. • Always a capital letter or a capital letter followed by a lower case letter. • Look at the periodic table in your agenda.

  6. Atoms that make up a molecule act as a unit • Molecule = a group of atoms that are held together by chemical forces; a molecule is the smallest unit of matter that can exist by itself and retain all of a substance’s chemical properties. • Some elements have to bind to other elements to survive in nature; others can exist on their own

  7. Compounds • Compound = a substance made up of atoms of two or more different elements joined by chemical bonds • Each molecule of a compound contains two or more elements that are chemically combined. • When compounds are made, elements always combine in the same proportions

  8. Compounds • Compounds have unique properties. • Properties can be different from the elements that make up the compound. • Formulas represent compounds

  9. Compounds You Need To Know • NaCl – Sodium Chloride • C6H12O6 – Glucose • HCl – Hydrochloric acid • HNO3 – Nitric Acid • CH3COOH – Acetic Acid • H2SO4 – Sulfuric Acid • NH3 – Ammonia • CaCO3 – Calcium Carbonate • H2CO3 – Carbonic Acid • C2H6O – ethanol • C6H12O6 – Galactose • H2O – Water • CH4 – Methane • H2O2 – Peroxide • CO – Carbon Monoxide • CO2 – Carbon Dioxide • C3H6O3 – Lactic Acid • C6H8O7 – Citric Acid

  10. Pure Substances vs Mixtures • Pure substance = a sample of matter, either a single element or a single compound, that has definite chemical and physical properties. • Mixture = a combination of two or more substances that are not chemically combined • Elements and compounds are pure substances, but mixtures are not.

  11. Mixtures • Classified by how well the substances mix. • Homogenous mixture = components are evenly distributed • Example: gasoline • Miscible = able to be mixed • Heterogeneous mixture = components are not evenly distributed • Example: salad

  12. Section 1 Review • Describe matter, and explain why light is not classified as matter. • State the relationship between atoms and elements. Are atoms and elements matter? • Give an example of molecules formed by 1 element and molecules formed by 2 elements. • State the chemical formula for water • List two types of pure substance.

  13. Section 1 Critical Thinking (TURN THESE QUESTIONS IN BEFORE YOU LEAVE) • Classify each of the following as element or compound: • Sulfur S8 Methane CH4 Carbon Monoxide CO Cobalt Co • Compare and contrast mixtures and pure substances • David says, “Pure honey has nothing else added.” Susan says, “Honey is not really pure. It is a mixture of many substances.” Who is right? Explain your answer.

  14. Properties of Matter

  15. Things You Need in Your Notes: • Terms: melting point, boiling point, density, flammability reactivity • Answers to the following questions: • Why are color, volume, and density classified as physical properties? • Why are flammability and reactivity classified as chemical properties

  16. Physical Properties • Characteristics that can be observed without changing the identity of the substance. • Can help identify substances, since properties remain constant and you can observe or measure them. • Melting point = temperature and pressure at which a solid becomes liquid • Boiling point = temperature and pressue at which a liquid becomes gas

  17. Common Melting & Boiling Points

  18. Density • Density = the ratio of the mass of substance to the volume of the substance • Density = mass/volume or D = m/V • It is expressed in grams per cubic centimeter (g/cm3) • 1 cm3 = 1mL

  19. Density vs Weight • A substance that has a low density is “light” compared to something else of the same volume. • Ex: Hot air balloon floats because cold air is less dense than hot air • A substance that has a higher density is “heavier” compared to another object of the same volume. • Ex: A rock sinks in water because it is more dense than the water.

  20. Chemical Properties • Reactive = the capacity of a substance to combine chemically with other substances. • Some elements react very easily with other elements. • Ex: Magnesium is very reactive, so it is used to make emergency flares. • Reactive elements are usually found as compounds in nature. • Some elements are not very reactive and must have a force acting on them to react. • Light bulbs are filled with argon gas because it is not reactive.

  21. Chemical Properties • A chemical property describes how a substance changes into a new substance, either by combining with other elements or by breaking apart into new substances. • Chemical properties are not as easily visible as physical properties. • Chemical properties are related to the specific elements that make up the substance.

  22. Flammability • Flammability = the ability to burn • A substance that does not burn, has the chemical property of nonflammability. • Ex: Gold

  23. Section 2 Review • List 2 physical properties & 2 chemical properties. • Identify the following as physical or chemical properties: 1. Reacts with water 2. is red 3. shiny & silvery 4. Melts easily 5. boils at 100°C 6. nonflammable 7. Low density 8. tarnishes in moist air

  24. Section 2 Critical Thinking ( You Must Turn This In at the End of Class • Describe several uses of plastic and explain why plastic is a good choice for these purposes. • Suppose that you need to build a raft. Write a paragraph (6-10 sentences) describing the physical and chemical properties of the raft that would be important for your safety.

  25. Changes of Matter

  26. What You Need to Know • Terms: physical change, chemical changes • Answers to the following questions: • Why is getting a haircut an example of a physical change? • Why is baking bread an example of a chemical? • How can mixtures and compounds be broken down?

  27. Physical Changes • Physical change = a change of matter from one form to another without a change in chemical properties. • A physical change affects one or more physical properties of a substance without changing the identity of the substance. • Ex: dissolving sugar in water, sanding wood, mixing oil and vinegar

  28. Physical Changes • Physical changes do not alter a substance’s identity. • During a physical change, energy is absorbed or released. • After a a physical change, a sample may look different, but the atoms are still arranged the same. • Dissolving is a physical change.

  29. Chemical Changes • Chemical change = a change that occurs when one or more substances change into entirely new substances with different properties. • The chemical properties of a substance describe which chemical changes can happen. • Chemical changes happen everywhere. • Ex: Battery dying, breathing, fruits and vegetables ripening, etc.

  30. Chemical Changes • Chemical changes form new substances. • Ex: Bread from ingredients • Chemical changes can be detected. • Ex: a change in odor or color, fizzing, a sound, heat, light • Chemical changes cannot be reversed by physical changes.

  31. Breaking Down Mixtures & Compounds • Mixtures can be separated by physical changes. • Ex: Distillation, evaporation, centrifuge • Compounds must be broken down by chemical changes. • Ex: electric currents, escaping carbon dioxide

  32. Section 3 Review • Explain why changes of state are physical changes. • Explain why physical changes can easily be reversed, but chemical changes can’t. • Identify 2 ways to break down a compound into simpler substances. • List 3 clues that indicate a chemical change.

  33. Section 3 Critical Thinking • Classify each of the following as either a physical or chemical change: Sugar added to lemonade water boiling egg frying Rust forming on metal fruit rotting evaporation of salt from water • Describe the difference between physical and chemical changes in terms of what happens to the molecules

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