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Chemical Symbols and Formulas. Chapter 2.7. 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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Chemical Symbols and Formulas Chapter 2.7
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. • 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.
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
Sodium comes from the word sodanum, a headache remedy, and it’s symbol (Na) comes from the Latin word Natrium.
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
Chemical Formulas - Examples • Calcium Carbonate (chalk) – CaCO3 • Sodium Chloride (salt) – NaCl • Acetysalicylic acid (aspirin) – C9H4O8 • Acetic acid (vinegar) – C2H4O2
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.
Homework • Do Questions #1–5 on Page 59 • You may use your Periodic Table. • Make sure that for each question you write out that question first then you write your answer and then continue on to the next question and so on until completed.
1 atom of sodium 2 atoms of hydrogen (in a hydrogen molecule) 3 atoms of magnesium 2 atoms of phosphorus 8 atoms of oxygen 13 total atoms 3 carbon atoms
Tomorrow Go over counting atoms worksheet Pass in Homework Chapter 2 quiz