Periodic Table
Ms. Copeland
Physical Science
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7
N
Nitrogen
14.0067
Atomic Number
7
N
Nitrogen
14.0067
7
Atomic Symbol
N
Nitrogen
14.0067
7
N
Element Name
Nitrogen
14.0067
7
N
Nitrogen
Mass Number
14.0067
Atomic Number
7
Atomic Symbol
N
Element Name
Nitrogen
Mass Number
14.0067
Atomic Number
• Tells You the number of Protons
• Nitrogen has 7 protons
Atomic Number
7
N
Nitrogen
14.0067
Every Element has a Neutral
Charge
• Protons are positive
• Nitrogen has a charge of +7 due to
Protons.
• There must be something that
balances the charge at zero.
• Electrons have a negative charge.
• So, Nitrogen must have a charge of
-7 due to electrons
• +7 + (-7) = 0
• BIG PICTURE: There are always
the same number of electrons and
protons in an element.
Atomic Number
7
N
Nitrogen
14.0067
Atomic Mass
• The Mass of an element is
measured in Atomic Mass
Units (AMU).
• The weight of a nitrogen Atom
is 14.0067AMUs.
• Electrons are much smaller
than protons and neutrons. To
include electrons in the weight
of an atom would be like
changing your weight
depending if you are holding a
grain or salt or not.
7
N
Nitrogen
14.0067
Mass Number
So how many neutrons are
Atomic Number
there in an atom?
• We know how to find the number of
protons and electrons in an element
• BOTH Protons and Neutrons are very
near the weight of 1 amu.
• There are 7 Protons in a Nitrogen Atom
and the Atomic Weight is about 14 AMUs
• So to find the number of neutrons you
should subtract the number of protons
from the atomic mass
• 14 AMUs - 7 protons (about 7 AMUs) = 7
neutrons (about 7 AMUS)
7
N
Nitrogen
14.0067
7
N
Nitrogen
14.0067
Mass Number
So How are Protons, Neutrons, and
Electrons Arranged in an Atom?
• Protons and Neutrons are found at the center
of an element in a very tight ball called the
nucleus. ALL protons and neutrons are found
here.
• Electrons are found “orbiting” the nucleus in
the electron cloud. The orbits found in the
electron cloud are highly structured. Electrons
want to be as close to the nucleus as possible
(opposites attract).
Electron Cloud Orbital
• Electrons follow a very precise way to
fill their orbital until you get to Scandium
on the periodic table.
• Transition metals follow very different
rules than other elements. Because of
this we will only cover the first 3 rows or
Periods 1, 2, and 3, which do not
contain Transition metals.
Bohr Diagrams
• Element’s ELECTRONS
in the first 3 periods fill
the inside orbital first.
• The first (inside) orbital
only holds two electrons.
• If there are electrons left
over, they fill the second
orbital.
• The second orbital only
holds 8 electrons.
• If there are still electrons
left over, they fill the third
orbital.
• The third orbital only
holds 8 electrons.
8
8
2
Bohr Diagram of Nitrogen
-Proton
-Neutron
• Nitrogen has 7
Electrons.
• The inside orbital
hold 2 electrons.
• 7 - 2 = 5 electrons
• 5 Electrons fill the
second orbital
• 5 - 5 = 0 electrons
• No electrons are
left, so the third
orbital is not
needed.
-Electrons
Where are the Protons and
Neutrons?
• Protons and
Electrons are
found tightly
clustered in a
ball in the
center of an
atom.
7
7
-Proton
-Neutron
-Electrons
Lewis Dot Structure
• The electrons found in the last orbital are called valence
electrons.
• Valence electrons are the electrons that are active in
chemical bonds.
• A Lewis Dot structure will help you determine how many
bonds are free to be made with other atoms
• In the center of a Lewis dot structure is the element’s
atomic symbol
• Only 8 valence electrons can be put around a Lewis Dot
structure
• When placing electrons around the Lewis Dot structure,
one goes on the left, bottom, right and top.
• If more than 4 valence electrons exist, they begin to
make pairs with the original 4 electrons.
Nitrogen’s Lewis dot structure
..
. .
N.
• Nitrogen has 5 electrons in it’s
outer shell.
• This means the Nitrogen has 5
valence electrons.
• Only one of Nitrogen’s sides has
a full pair.
• 3 sides of Nitrogen’s Lewis Dot
structure does not make full
pairs.
• Nitrogen has 3 spots capable of
being involved in a chemical
What does a full Lewis Dot
Structure Look Like?
.. .
.. .
Ar
..
• Argon has 8 valence electrons
• Argon cannot react with other
chemicals
• All elements in the 18th column
have full Lewis Dot structures
• Because no elements in the 18th
column (group) can react with other
elements, they are called noble
• All of the elements in Group 18 are
gases at room conditions.
• Elements in Group 18 are called
NOBLE GASES.