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A brief review of Chemistry

A brief review of Chemistry. A few general terms…. Anything that takes up space is termed matter. An element is a substance that cannot be broken down into simpler substances. . Elements.

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A brief review of Chemistry

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  1. A brief review of Chemistry

  2. A few general terms… • Anything that takes up space is termed matter. • An element is a substance that cannot be broken down into simpler substances.

  3. Elements • Elements are represented by a large letter (or letters) (such as C, N, Na or O) on a large chart called the periodic table.

  4. Symbols you should memorize(Quiz next time) • Carbon = • Sulfur = • Potassium = • Nitrogen = • Hydrogen = • Phosphorus = • Sodium = • Iron = • Oxygen = • Chlorine = • Copper =

  5. The smallest particle of an element which retains the characteristics of that element is an atom.

  6. On the diagram of an atom bellow, label the: • Protons with an A • Electrons with a B • Neutrons with a C • How many protons are there? _____ • How man electrons are there? ____ • How many neutrons are there? ____ • Using the periodic table, can you figure out what element this is? • Hint: Atomic number = the number of protons in the nucleus

  7. When two or more elements come together to form a new product, the process is called a chemical reaction. • The resulting product, which is a new combination of elements is called a compound.

  8. Every compound has a unique formula which shows how many atoms of each are in the compound. (eg. CO2) • The smallest unit of a compound that still retains the properties of the compound is called a molecule.

  9. Mixtures and Solutions

  10. Any two substances that are not chemically combined but are together is called a mixture.

  11. A solution is a class of mixtures in which the molecules are evenly distributed. • The substance being dissolved is the solute. • The medium in which the substance is being dissolved is called the solvent.

  12. Molecules that can be dissolved are termed soluble. • Molecules that cannot be dissolved are termed insoluble.

  13. Acids and Bases

  14. The pH scale measures the acidity or basicity of a substance. • An indicator is a chemical used to test for pH. • An acid or base usually produces a color change in the indicator. • Electricity is also used to measure pH. http://www.fossweb.com/

  15. Acids • An acid has a high concentration of dissolved H+ ions. • It has a pH less than 7 • Some examples of acids are sulfuric acid (H2SO4); hydrochloric acid ( HCl) and acetic acid (CH3COOH)

  16. Bases • A base has a high concentration of OH- ions. • It has a pH of more than 7. • Some examples of bases are ammonia (NH3) and acetate ion (C2H3O2-).

  17. Introduction to chemical Reactions

  18. What does the word “chemical” mean to you? • Chemical: a single substance with distinctive properties • All matter is in the form of chemicals. • A chemical always reacts the same way under any given circumstance.

  19. What is the difference between a chemical change and a physical change?

  20. Chemical Change: a new chemical is formed • Examples: rusting, rotting, burning • Signs of a chemical change – color change, release of gas, new substance formed, energy released

  21. Physical Change: NO new chemical is formed • Examples: breaking, dissolving, boiling, evaporating, melting, eroding, freezing, grinding, subliming

  22. Indentify which of the following are chemical (C) or physical (P) changes: • a solid stretches when gently pulled ___ • a powder dissolves in water __ • a solid burns when ignited __ • a liquid changes color when exposed to air for a long time __ • a solid shatters into small pieces when hit with a hammer __ • a gas “pops” when a burning match is placed close by __ • solid becomes a gas when slightly warmed __ • a liquid evaporates in hot weather __ • limewater becomes cloudy when a gas passes through it __

  23. A chemical change is also called a “chemical reaction.” How do we write a chemical reaction? • Where are the “reactants” in an equation? • Where are the “products” in an equation? • What is the term for all the chemical reactions that occur in an organism? • Metabolism

  24. Types of Reactions • Synthesis reactions: ANABOLISM A + B  AB atoms, ions, or molecules combine to form a new molecule • Example: combining of amino acids to form proteins

  25. Types of Reactions • Decomposition Reactions: CATABOLISM AB  A + B Molecule breaks apart to form atoms, ions, or molecules • Example: chemical digestion of food particles into basic nutrients

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