- 1 - CHEMISTRY 2 REVIEW: MIDTERM Everything Energy Matter ...

Flame Test
• A flame test can be used to identify a METAL.
• An electron falling from an excited state will release energy in the
form of colored light.
• The color of the light depends upon the energy of the transition.
o Red – lowest energy
o Violet – highest energy
Counting Atoms
1. The symbol of an element represents 1 atom
Example: Na = 1 atom of sodium
2. A subscript indicates the number of atoms of a particular
element
Gas
Example: H2 = 2 atoms of hydrogen
3. A subscript outside of parentheses multiplies all elements
inside the parentheses
Example: Al(OH)3 = 1 aluminum, 3 oxygen, 3 hydrogen
4. A coefficient in front of a symbol indicates the number of
that element
Liquid
Example: 3 C = 3 atoms of carbon
5. A coefficient in front of a chemical formula indicates the number of molecules of that compound and
multiplies the number of atoms of each element in the formula
Example: 3 N2O4 = 3 molecules or 6 atoms of nitrogen, 12 atoms of oxygen
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Solid