Chemical Formulas, Equations and Reactions Notes

Atom The smallest particle of any pure element. Only 1 atom Example: 1 atom of H

Element A substance made up of the SAME type of atom Example: O2

Compound -a substance made up of atoms of two or more DIFFERENT elements combined in a specific ratio Ex. NaCl or H2O

Molecule -Group of 2 or more atoms -Atoms may or may not be of the same element EX. NaCl or O2

Atom Element Compound Molecule C, O, H, N C,C2, O, O2, H, H2, N,N2 CH4, H2O, CO2 CH4, H2O, H2, O2, CO2 2H2O, 3O2, 2CO2

Chemical Formula -a way of describing the number of atoms that make up one molecule of a compound Ex. C6H1206 H20

Subscript -the number of atoms of that particular element SUB-Below EX. H20 or CH4

Coefficient EX. 2H2O 4Al2(SO4)3 -determines the number of molecules (groups) of the formula -This number will be DISTRIBUTED just like in math. It applies to each element and is multiplied by each subscript to find the total number of atoms of each element and a total number of atoms in the molecule. EX. 2H2O 4Al2(SO4)3

CH4 H C H H H

2H20 H H H H O O

4Fe2O3 NaClO 2FeCl3 ZnCl2 KMnO4 KClO3 3HgO 24F2 C6H5COOH 3Al2(SO2)3 Identify the Elements, give the number of atoms of each element, and the total number of atoms in the formula 4Fe2O3 NaClO ZnCl2 KClO3 24F2 3Al2(SO2)3 2FeCl3 KMnO4 3HgO C6H5COOH 2HCl

Chemical Reaction -a change in which one or more chemical substances are rearranged to form different substances.

Reactants Products Chemical Equation -a way to show a chemical reaction using chemical formulas. -made up of reactants and products Yields Reactants Products

Yield the amount of product obtained as a result of a chemical reaction 

Components of chemical reaction Products -are indicated on the right side -new substances created/PRODUCED in a chemical reaction -Outputs -Cake Reactants -are indicated on the left side -substances that react in a chemical reaction -inputs -Ingredients

Example CH4 + 2O2  CO2 + 2H2O Reactants Products Coefficient (# of molecules) # of atoms of that element

Law of Conservation of Mass -what goes into a chemical reaction will come out of a chemical reaction. -atoms found on the reactants side will also be found on the products side. They will be broken apart and rearranged to create new substances. -creates a “Balanced” equation CH4 + 2O2  CO2 + 2H2O

Photosynthesis 6CO2 + 6H2O  C6H12O6 + O2

4P + 5O2  P4O10 Mg + O2  MgO 2Al2O3  4Al + 3O2 2HgO  2Hg + O2 Modeling Balanced/Unbalanced Equations Identify whether the chemical reaction is balanced or unbalanced 4P + 5O2  P4O10 Mg + O2  MgO 2Al2O3  4Al + 3O2 2HgO  2Hg + O2 BaCl2 + H2SO4  BaSO4 + HCl

Identify Balanced Equations 2Fe + 3Cl2  2FeCl3 KMnO4 + HCl  KCl + MnCl2 + H2O + Cl2 HgO  Hg + O2 C6H5COOH + O2  CO2 + H2O H2 + Cl2  2 HCl 2Fe + 3O2  Fe2O3 2NaOH + Cl2  NaCl + NaClO + H2O Zn + 2HCl  ZnCl2 + H2 KClO3  KCl + O2 S8 + 24F2 8SF6

Signs of Chemical Changes

Chemical Property -The ability of a substance to undergo a change that alters its identity. -A characteristic that cannot be observed without altering the substance

Chemical Change Change in which the composition of a substance changes Changes are not easily reversed

Signs of Chemical Changes Change in Color Change in Temperature 3. Change in Odor Bubbles- Gas produced 5. Precipitate (solid) is formed

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