atoms vs. molecules atom – the smallest unit of an element that maintains the properties of that...
TRANSCRIPT
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: CO2, O2, NaCl, C6H12O6
For a molecule to be a compound it must contain atoms of at least two different elements.
Counting Atoms Practice
K2CO3
Ca(C2H3O2)2
NaBr
Al(OH)3
2 6
15 7
Parts of a Chemical Equation
YIELDS
COEFFICIENT SUBSCRIPT
Reactants MUST Equal Products (Law of Conservation of Matter)
Counting Atoms Practice with Coefficients
4K2CO3
2Ca(C2H3O2)2
12NaBr
4Al(OH)3
6Ba(MnO4)2
5Ga2(Cr2O7)3
24 24
30
145
28
66
Are They Balanced??
Reactants MUST Equal Products (Law of Conservation of Matter)
Na2O2 + H2O4NaOH + O2
Zn + AgNO3
Zn(NO3)2 + 2AgAl + MnO
Al2O3 +3Mn
NH3 +HClNH4Cl
NOT BALANCED7 14
6
6
3
11
8
6
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. Na2O2 + H2O 4NaOH + O2
2. Zn + AgNO3 Zn(NO3)2 + 2 Ag
3. Al + MnO Al2O3 + 3Mn