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How to Obtain the Number of Sub-Atomic Particles in
an Atom Using a Periodic Table
-
+
-
++ +
+ + +
+
+
= 8
= 8
-
-
= 8
-
Protons
Neutrons
+
Electrons
-
Equal to the atomic #
on the Periodic Table
Equal to the atomic mass
(rounded to a whole #)
minus the # of protons
Equal to the # of
protons
Example: Determine the # of protons, neutrons, and electrons in an atom of oxygen.
Protons = 8 (Atomic #)
Neutrons = 8 (Rounded atomic mass minus atomic #)
Neutron Calculations = 16 (P + N) – 8 (P) = 8 N
Electrons = 8 (# of P)
How to Obtain the Number of Sub-Atomic Particles in
an Ion Using a Periodic Table
-
-
-
2-
Notice
how two
electrons
have been
gained by
the atom,
thus
resulting in
an ion
+
= 8
++ +
+ + +
+
+
-
= 8
-
= 10
8
-
Neutrons
Protons
-
-
Electrons
+
Equal to the atomic #
on the Periodic Table
-
-
Equal to the atomic mass
(rounded to a whole #)
minus the # of protons
Equal to the # of protons plus the # in
the upper right corner if followed by a
(-) OR minus the # in the upper right
corner if followed by a (+)
Example: Determine the # of protons, neutrons, and electrons in the oxygen ion O²¯.
Protons = 8 (Atomic #)
Neutrons = 8 (Rounded atomic mass minus atomic #)
Neutron Calculations = 16 (P + N) – 8 (P) = 8 N
Electrons = 10
Electron Calculations = 8 (e) + 2 (e) = 10