Chemical Formulas

Chemical Formulas 

Molecule - Two or more atoms joined together chemically. 

Subscript - the number written after an element's symbol in a chemical formula that indicates the number of atoms of a specific element. 

Coefficient - the number in front of an element or compound that indicates the number of molecules in a chemical formula.

Chemical Equations

Reactants - elements or compounds on the left side of a chemical equation.

Products - elements or compounds on the right side of a chemical equation Balanced Equation - the number of atoms for each element are equal for the reactants and products Unbalanced Equation - the number of atoms for each element is not equal for the reactants and products.

Law of Conservation of Mass - matter cannot be created or destroyed.

Balanced and Unbalanced Chemical Equations 

• Find the number of atoms of each element on the reactant side. 
• Find the number of atoms of each element on the product side.
• If the number of atoms of each element is the same on the reactant and product side then the equation is balanced.
• If the number of atoms of each element is NOT the same then the equation is unbalanced. 

Chemical Reactions 

Chemical Change - the type of change that results in the formation of new chemical substances. 

Physical Change - the type of change in which the form of matter is altered, but one substance is not transformed into another. 

Chemical Property - a characteristic that can only be determined by changing the identity of a substance. 

Physical Property - a characteristic that can be observed a measured without changing the composition of a substance.

Evidence of a Chemical Reaction- a chemical reaction has occurred if any of the following take place: unexpected temperature change, unexpected color change, production of gas, change in odor, or formation of a precipitate.