Atoms vs. Molecules Atom – the smallest unit of an element that maintains the properties of that element. Ex: C, O, He, Hg Molecule – two or more atoms joined in a definite ratio. Ex: CO 2, O 2, NaCl, C 6 H 12 O 6 For a molecule to be a compound it must contain atoms of at least two different elements.

Counting Atoms Practice K 2 CO 3 Ca(C 2 H 3 O 2 ) 2 NaBr Al(OH)

Parts of a Chemical Equation YIELDS COEFFICIENT SUBSCRIPT Reactants MUST Equal Products (Law of Conservation of Matter)

Counting Atoms Practice with Coefficients 4K 2 CO 3 2Ca(C 2 H 3 O 2 ) 2 12NaBr 4Al(OH) 3 6Ba(MnO 4 ) 2 5Ga 2 (Cr 2 O 7 )

Are They Balanced?? Reactants MUST Equal Products (Law of Conservation of Matter) Na 2 O 2 +H 2 O4NaOH+O 2 Zn+AgNO 3 Zn(NO 3 ) 2 +2Ag Al+MnOAl 2 O 3 +3Mn NH 3 +HClNH 4 Cl NOT BALANCED NOT BALANCED BALANCED

How Will I Know?? Signs of a Chemical Reaction Chemical Reaction Definition: The process of one or more substances changing to produce new substances. (VERY SIMILAR to a Chemical Change!) Gas Formation; Precipitate formation (solids settle to the bottom); Thermal Energy Change (heat/light given off); Color Change; Effervesces (BUBBLES!!); Odor (smell)

What happens to chemical bonds during a chemical reaction? Bond are broken down. Atoms are rearranged. New bonds are formed to create new substances with different physical and chemical properties.

How Can We Manipulate Reactions?? Speed Up Slow Down Law of Conservation of Energy…Whatever Energy you START with you MUST finish with…Energy CANNOT be created or destroyed!! Increase the temperature; Increase the concentration of the reactant; Grind reactants into smaller pieces (reduce the surface area); Agitate (stir quickly); add a Catalyst (something to speed up a reaction) Decrease the temperature; Decrease the concentration of the reactant; Use large/solid pieces of reactants); Add an inhibitor (something to slow a reaction)

Romantic Reactions See how some of your favorite characters react together…there will be laughter, love, tears, and anger. Types of Chemical Reactions As told by our media addictions…

Synthesis Reaction Two or more simple substances combine to form a more complex substance.

Decomposition Reaction A complex substance breaks down into two more simpler substances. Reverse of a synthesis reaction.

Single Replacement Reaction A single element replaces one element in a compound. The product of a single replacement reaction are a new compound and a single element.

Double Replacement Reaction Two new compounds form. The element with the positive oxidation state in one compound changes places with the positive oxidation state element in the other compound.

Practice – Balancing Equations 1.Na 2 O 2 + H 2 O  4NaOH + O 2 2.Zn + AgNO 3  Zn(NO 3 ) Ag 3.Al + MnO  Al 2 O 3 + 3Mn