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2.2: Chem Formulas & Eqns

2.2: Chem Formulas & Eqns. Chemical symbols make chemical formulas just as letters make words Chemical formulas can be placed together to describe chemical rxns. 2.2: Chem Formulas & Eqns. Chemical Formula A shortened way using chemical symbols and numbers to represent a substance

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2.2: Chem Formulas & Eqns

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  1. 2.2: Chem Formulas & Eqns • Chemical symbols make chemical formulas just as letters make words • Chemical formulas can be placed together to describe chemical rxns

  2. 2.2: Chem Formulas & Eqns • Chemical Formula • A shortened way using chemical symbols and numbers to represent a substance • Shows how many atoms are present in each molecule

  3. 2.2: Chem Formulas & Eqns • Chemical Formula • Subscripts are used to indicate how many of each atom are present 2 hydrogen atoms H2O 1 oxygen atom subscript

  4. 2.2: Chem Formulas & Eqns • Chemical Formula • Subscripts • If a subscript is not present with a chemical symbol, there is only 1 of that atom in the compound

  5. 2.2: Chem Formulas & Eqns • Formulas for Covalent Compounds • A covalent compound is made of 2 or more nonmetals • Prefixes are used to indicate the number of atoms of each element in the chemical formula

  6. 2.2: Chem Formulas & Eqns • Prefixes you must know

  7. 2.2: Chem Formulas & Eqns • Formulas for Covalent Compounds • If the there is only 1 atom of the first nonmetal in a covalent compound, we do not usually use the prefix “mono” • CO2 – carbon dioxide • SO3 – sulfur trioxide

  8. 2.2: Chem Formulas & Eqns • Formulas for Ionic Compounds • An ionic compound is made of a metal and nonmetal

  9. 2.2: Chem Formulas & Eqns • Formulas for Ionic Compounds • To write formula for an ionic compound, you need to figure out the charge that each ion will form • Use enough of each ion so the overall charge is 0

  10. 2.2: Chem Formulas & Eqns • Formulas for Ionic Compounds • Try this short cut: Na1+ Cl1- NaCl Mg2+ Cl1- MgCl2

  11. 2.2: Chem Formulas & Eqns • Chemical Eqns • Uses chemical symbols and formulas as a shortcut to describe a chemical rxn • Understood by scientists around the world

  12. 2.2: Chem Formulas & Eqns • Chemical Eqns • Reactants • The starting material in a rxn • Left side of equation • Products • The end material in a rxn • Right side of the equation

  13. 2.2: Chem Formulas & Eqns • Chemical Eqns • The arrow is the “yield sign”, and separates the products and reactants • A plus (+) sign separates 2 or more reactants

  14. 2.2: Chem Formulas & Eqns • Balancing Chemical Eqns • Coeffient • Numbers placed in front of chemical symbols or formulas • NEVER CHANGE SUBSCRIPTS WHEN BALANCING AN EQN • This changes the compound

  15. 2.2: Chem Formulas & Eqns • Chemical Eqns • Law of Conservation of Mass • Mass is neither created or destroyed in ordinary chemical or physical changes • Atoms must be equal on each side of a chemical equation

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