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Chemical Formulas Coefficient Subscript #of molecules 5CO2 #of atoms.

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Presentation on theme: "Chemical Formulas Coefficient Subscript #of molecules 5CO2 #of atoms."— Presentation transcript:

1 Chemical Formulas Coefficient Subscript #of molecules 5CO2 #of atoms

2 Chemical Reactions- takes place when chemical bonds between atoms are broken and new bonds form. There are the same number of total atoms of each element at the end.

3 Chemical Equations- Ex) Na + Cl NaCl reactants products
Reactants - the chemicals to be combined (left of the arrow) Products - Results of the combinations (right of the arrow) Ex) Na + Cl NaCl reactants products

4 3 Rules to Balancing Equations
1. Check to make sure all formulas are written correctly. 2. Do NOT change subscripts in formulas. Only change coefficients.

5 A coefficient of 2 must be placed in front of Na to be balanced!
Coefficients- Numbers placed in front of a formula to make the number of atoms on each side of the equation equal. Ex) Na + Cl NaCl Na is NOT equal! A coefficient of 2 must be placed in front of Na to be balanced! 2Na + Cl NaCl

6 Count atoms, then begin with an element that only occurs once on each side of an equation.
Ex. A) H H2O Which element is not equal? 1. H2 +O H O = H ≠ 2H2 + O H2O balanced!

7 Ex. B) Na + 2H20 NaOH + H2 Which element is not equal?
Coefficient of 2 added to NaOH Na + 2H NaOH + H O= H= Na ≠ 2Na + 2H NaOH + H2

8 4 Types of Chemical Reactions
Synthesis Reaction Reaction in which two or more substances combine to forms a compound. Sodium + Chloride Salt 2Na + Cl NaCl

9 Decomposition Reaction
Compound breaks into two or more substances. 2HgO Hg + O2

10 Single Replacement Reaction
One element replaces another element in a compound to form a new compound Fe + CuSO FeSO4 + Cu

11 Double Replacement Reaction
Occurs when two compounds in a reaction exchange atoms AgNO3 + NaCl AgCl + NaNO3


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