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Matter: Elements, Compounds, and Mixtures

Delve into the world of matter with this comprehensive guide, covering elements, compounds, and mixtures. Learn about atoms, molecules, and pure substances versus mixtures. Explore properties such as melting point, boiling point, density, and more. Equip yourself with the knowledge needed for a quiz grade binder check.

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Matter: Elements, Compounds, and Mixtures

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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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