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The Chemistry of Life
Counting Atoms
Three Subatomic
Particles:
Charge
Location
Proton
+1
Nucleus
Neutron
0
Nucleus
Electron
-1
Electron cloud
Atomic Number


The number of
protons in an
atom
Unique for every
element
Atoms are always
electrically neutral.
This means that protons
always equal the
electron.
How many protons &
electrons are in the
following atoms?

Silicon

14 p & 14 e

Nitrogen

7p&7e

Zinc

30 p & 30 e
Mass Number


The number of
protons and
neutrons in the
nucleus
Mass Number –
Atomic Number =
Neutrons
How Many Neutrons are
in:

Potassium

20 n

Argon

22 n

Tin

69 n
Atomic Structure
Lithium
Phosphorus