1. Atomic Masses
16.2

2. Quark – smaller particles that make up protons and neutrons
Smaller particles of matter called quarks exist, but scientists still consider atoms the basic building blocks of matter.
Quark – smaller particles that make up protons and neutrons
– six quarks are known to exist

3. Atomic number – the number of protons in an atom
Atomic mass – composed mostly of protons and neutrons in the nucleus – called the mass number
Atomic number – the number of protons in an atom
Elements are identified by their atomic number

5. Atomic number = # of protons # of electrons = # of protons
If you need to find # of neutrons of an atom:
# of neutrons = mass number – atomic number
Atomic number = # of protons
# of electrons = # of protons
# of neutrons = mass number – atomic number

6. Isotopes – atoms of the same element that have different number of neutrons
Ex: B or B11
Boron Boron11
Different isotopes have different properties.

7. Average atomic mass – weighted average mass of an element’s isotopes
Common Mass Numbers
Element
Symbol
Atomic #
# Protons
# Neutrons
Mass #
Avg. Atomic Mass
Boron B 5 6 11
11.81 amv
Carbon C 12
12.01 amv
Oxygen O 8 16
16 amv
Sodium Na 23
22.99 amv
Copper Cu 29 34 63
63.55 amv

8. Construct a time line that will show the development of the atomic theory.
Include: date, name of scientist, statement of their theory, illustration of their model
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