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Elements, Compounds and Mixtures

Elements, Compounds and Mixtures. Elements Reminder. An element is a pure substance that cannot be separated or broken down into simpler substances by physical or chemical means. A pure substance is a substance in which all of the “building-block” particles are identical.

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Elements, Compounds and Mixtures

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  1. Elements, Compounds and Mixtures

  2. Elements Reminder • An element is a pure substance that cannot be separated or broken down into simpler substances by physical or chemical means. • A pure substance is a substance in which all of the “building-block” particles are identical. • For elements, the building-block particles are called atoms.

  3. Elements Questions • 1. A property of an element that does not depend on the amount of the element is called: • A. electromagnetic property • B. Finite property • C. Unique property • D. Characteristic property • 2. How are metalloids NOT similar to metals? • A. they have some properties of nonmetals • B. Some are shiny, while others are dull • C. They are somewhat malleable and ductile • D. Some are good conductors of electrical current.

  4. Compounds • A compound is a substance composed of two or more elements that are chemically combined. • Elements combine by reacting, or undergoing a chemical change, with one another. • A chemical reaction is the process by which substances change into new substances.

  5. Compound – elements combine • During a chemical reaction, the atoms of two or more elements react with each other to form molecules of compounds. • When two or more elements combine, a new compound is formed. The properties of the new compound are different from the properties of the elements that formed the compound. • Common compounds = Salt (sodium and chlorine), Water = (hydrogen and oxygen)

  6. Chemical Reactions • Watch the magnesium burn – it is reacting with oxygen to form a COMPOUND – Magnesium Oxide. • Magnesium Oxide is different from the elements Magnesium and Oxygen

  7. Properties of Compounds • Each compound has unique physical and chemical properties. • A compound has properties that differ from the properties of the elements that make up the compound. • Elements always join in a specific ratio to form a specific compound. Salt is 39.34% sodium and 60.66% chlorine

  8. Breaking Down Compounds • The only way to break down a compound is through a chemical change. • Some compounds can be broken down into their elements. • Other compounds can be broken down to form simpler compounds instead of elements.

  9. Compounds in Your World • Compounds are all around you. They make up the food you eat, your clothes, even you! • The compounds found in nature are not usually the raw materials needed by industry. Often, these compounds must be broken down to provide elements or other compounds that can be used as raw materials. (aluminum oxide) • Proteins and carbon dioxide are two compounds that play an important role in living things.

  10. Compounds Questions • 1. When two or more elements join together chemically, • A. a compound is formed • B. a mixture is formed • C. a substance that is the same as elements is formed • D. the physical properties of the substance remains the same. • 2. The physical properties of compounds do NOT include • A. melting point. C. reaction to light • B. density D. color

  11. More Compounds Questions 3. By what process can compounds be broken down? -a. physical changes -b. chemical changes -c. compound changes -d. either physical or chemical changes 4. Which of the following is NOT true of compounds? • The unique set of properties of a compound differ from the properties of the elements that make the compound. • The particles are made of atoms of elements that are chemically combined • Different samples of any compounds have the same elements in the same proportion • They can be separated by physical means

  12. Mixtures • A mixture is a combination of two or more substances that are not chemically combined. • Each substance in a mixture keeps its identity because no chemical change happens when a mixture is made. • Mixtures can be separated by physical means, such as filtration, evaporation, and distillation. • The components of a mixture do not need to be mixed in a definite ratio.

  13. Examples of Mixtures • Rocks (granite is made of felspar, mica and quartz) • Pizza • Salad Dressing • Lemonade

  14. Separating Mixtures • If you don’t like mushrooms you can just pick them off your pizza. That is separating the mixture. • Not all mixtures are easy to separate. • Ways to separate mixtures: Distillation, Magnet, Centrifuge, Dissolving- Filtering-Evaporating

  15. Mixtures Vs. Compounds

  16. Mixtures Questions • Pick from these words: ratio, nitrogen, concentration, distillation, dilute • A mixture of liquids can be separated by ______________? • Solutions can be described as being concentrated or _________. • The amount of a substances in a given quantity of a mixture, solution or ore is known as the ___________.

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