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Unit 1A ACS Chemistry in the Community Sixth Edition

Unit 1A ACS Chemistry in the Community Sixth Edition. Chemical Symbols and Formulas. Unit 1.A.6 and 7. Chemical Symbols. All elements in the Periodic Table have symbols that are recognized world wide . It does not matter which country you are in or the language you speak.

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Unit 1A ACS Chemistry in the Community Sixth Edition

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  1. Unit 1A ACS Chemistry in the Community Sixth Edition

  2. Chemical Symbols and Formulas Unit 1.A.6 and 7

  3. Chemical Symbols • All elements in the Periodic Table have symbols that are recognized world wide. • It does not matter which country you are in or the language you speak. • Example: The element Iron is always identified by “Fe” and Oxygen is “O”. • The names are not always the same but the symbols are. “Fe” is iron in Canada, fer in France and fier in Romania.

  4. Chemical Symbols A Chemical symbol is an abbreviation of a name of an element. Capital letter if only one letter. Only first letter capital if more than one letter

  5. Sodium comes from the word sodanum, a headache remedy, and it’s symbol (Na) comes from the Latin word Natrium.

  6. Chemical Formulas A chemical formula is the combination of symbols that represent a particular compound. The chemical formula indicates which elements are present in the compound and in what proportions. Ex. 1: Water molecule H2O: 2 atoms of hydrogen, 1 atom of oxygen Ex. 2: Iron Oxide molecule Fe2O3: 2 atoms of iron, 3 atom of oxygen

  7. Chemical Formulas - Examples • Calcium Carbonate (chalk) – CaCO3 • Sodium Chloride (salt) – NaCl • Acetysalicylic acid (aspirin) – C9H4O8 • Acetic acid (vinegar) – C2H4O2

  8. Chemical Formulas • NOTES: - Each symbol in a formula represents an element. - If only one atom of an element is present in the compound, no subscript is used. - If more than one atom of an element is used, then the symbol is followed by a number indicating how many atoms are used. This is called the subscript.

  9. Chemical Reactions

  10. I. CHEMICAL EQUATIONS A. Definitions 1. Chemical Equation - represents reactants and products in a reaction using symbols, formulas and coefficients. 2. Subscript - indicate the number of atoms of an element in a chemical reaction. 3. Coefficient - whole number in front of a formula or symbol that indicates the number of atoms, molecules, formula units or moles

  11. Subscripts vs. Coefficients • The subscripts tell you how many atoms of a particular element are in a compound. The coefficient tells you about the quantity, or number, of molecules of the compound.

  12. CHEMICAL REACTIONS Reactants: Zn + I2 Product: Zn I2

  13. Methods for Writing Equations 1. word equation – reactants and products are represented by words 2. formula equation- reactants and products are represented by element symbols and formulas 3. balanced chemical equation – a formula equation using coefficients to represent the number of atoms, molecules, or formula units

  14. Symbols Used in Writing Equations 1. --------> yields, forms, produces, reacts to form 2. --------> reversible reaction (products <--------- react to re-form the reactants) 3. symbols or words written above -----> a.triangle– reaction requires heat b. oC– indicates temperature required c. atm– indicate pressure is required d. symbol for element or formula for compound – catalyst is required

  15. letters or symbols next to formula a. letters (s) – solid (l) – liquid (g) – gas (aq) – aqueous solution b. symbols arrow point up – gas produced arrow pointingdown–precipitate forms

  16. Chemical Equations 4 Al(s) + 3 O2(g) ---> 2 Al2O3(s) This equation means 4 Al atoms + 3 O2 molecules ---produces---> 2 molecules of Al2O3 AND/OR 4 moles of Al + 3 moles of O2 ---produces---> 2 moles of Al2O3

  17. http://www.youtube.com/watch?v=d58UcB_Yb2Q • 1.  Define the terms “reactants” and “products.” Give examples of each from a chemical equation. • 2. What do all chemical reactions need? • 3. What do you think EA stand for? • 4. What role does a catalyst play in a chemical reaction?

  18. CHEMICAL REACTIONS • Bonds and Chemical Reactions 1. bonds form, break or both 2. atoms combine, separate, rearrange A + B  A-B C-D  C + D A-B + C  C-B + A C-D + B  C-B + D A-B + C-D  A-D + C-B

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