7.4 Making Molecular Models
7.5 What Is This Gas?
Limewater: 石灰水
Incomplete combustion is the type of combustion in which there is not enough oxygen or a high enough
temperature for the carbon to turn into carbon dioxide. This can sometimes lead to the production of carbon
monoxide, which is very harmful to the human body. Incomplete combustion will produce a yellow flame. An
example of an incomplete combustion is burning paper because there are remnants of ash.
Complete combustion is when the substance is completely burned and only carbon dioxide and water remain.
many magicians use paper with extra oxygen molecules. This special paper will burn completely leaving no traces
when burned. Complete combustion produces a more orange or blue flame.
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7.6 Breaking Molecules Apart: Properties of Hydrogen Peroxide
Peroxide: a compound containing an oxygen–oxygen single bond or the peroxide anion, O2. The O−O group is
called the peroxide group or peroxo group.
*Note:
Two guys walk in to a bar
First guy says "ill have some h2o"
Second guy says "sounds good. I’ll have some h2o too!"
The second guy died later
Catalyst: a substance that speeds up a chemical reaction but is not used up in the reaction.
7.8 DDT Is Forever
DDT ("dichlorodiphenyltrichloroethane") is a colorless, crystalline, tasteless and almost odorless
organochloride known for its insecticidal properties.
Writing Chemical Equations:
Writing Word Equations:
Using your naming rules you can write chemical equations using the names of compounds.
Example:
NaCl + CaO -> CaCl2 + Na2 O
Sodium chloride + calcium oxide -> calcium chloride + sodium oxide
*note: why calcium chloride instead of calcium dichloride?
H2O2 -> H2 + O2
dihydrogen dioxide -> hydrogen + oxygen
Mg + AlCl3 -> Al + MgCl2
magnesium + aluminum chloride -> aluminum + magnesium chloride
Are elements that when you write them by themselves get a subscript of 2. They are the ONLY ones that get
subscripts – all others are just 1.
H2 ,O2 ,Br2, F2, I2, N2, Cl2
 When you are giving a word equation you must use your naming rules to come up with the chemical
equations.
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Sodium + water  hydrogen and sodium oxide
Na + H2O  H2 + Na2O
Nitrogen + oxygen  dinitrogen trioxide
N2 + O2  N2O3
Atomic Radii – Size of an atom. The atomic radius tend to increase going down any periodic table group and
increase from right to left(with the exception of the noble gases).
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Questions:
What is known as the octet rule?
What are oxidation numbers and why are they important?
What are valence electrons and why are they so important in chemical bonding?
What is the difference between covalent and ionic bonding?
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