1. I. Structure of the Atom Chemical Symbols Subatomic Particles
Atomic Structure
I. Structure of the Atom
Chemical Symbols
Subatomic Particles

2. Metal that forms bright blue solid compounds.
p.270 QUIZ ON
Thursday 9/13
A. Chemical Symbols
Capitals matter!
Element symbols contain ONE capital letter followed by lowercase letter(s) if necessary.
Metal that forms bright blue solid compounds.
Co vs. CO
Poisonous gas.

3. B. Subatomic Particles in a neutral atom Most of the atom’s mass.
NUCLEUS
ELECTRONS
in a neutral atom
PROTONS
NEUTRONS
NEGATIVE CHARGE
POSITIVE CHARGE
NEUTRAL CHARGE
Most of the atom’s mass.
Atomic Number
equals the # of protons

4. C. Atomic Mass atomic mass unit (amu)
1 u = 1/12 the mass of a 12C atom
1 proton = 1 u 1 neutron = 1 u
Mass of proton and neutron are basically the same.
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5. The mass of an electron is so small that it is not counted in the Atomic Mass!

6. D. Atomic Number Number of protons only!
Identifies the type of element
If it has a different # of protons it is a different element.
Atomic Number is on the Periodic Table.
In a neutral atom protons=electrons

7. E. Mass Number
Sum of the protons and neutrons in the nucleus of an atom.
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Always a whole number.
Mass # = protons + neutrons

8. F. Isotopes Mass # Atomic #
Atoms of the same element with different numbers of neutrons.
Isotope symbol:
Mass #
Atomic #
“Carbon-12”

9. F. Isotopes
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10. C. Isotopes Average Atomic Mass reported on Periodic Table
weighted average of all isotopes
Avg.
Atomic
Mass

11. C. Isotopes
EX: About 8 out of 10 chlorine atoms are chlorine-35. Two out of 10 are chlorine-37.
Avg.
Atomic
Mass
35.4 u