Download Atomic Structure and the Periodic Table

Atomic Structure and the
Periodic Table
Protons, Neutrons, Electrons and
What Those Numbers Mean

1.
2.
When classifying elements on the
Periodic Table, 2 different methods are
used:
The Atomic Number of an element
The Atomic Mass of an element
What is Atomic Mass?
The average mass
of an atom of an
element.
2. The sum of the
number of protons
added to the sum of
the number of
neutrons.
1.
Find the atomic mass of the
following:
1.
2.
3.
4.
5.
6.
Lithium
Element number
30
Ar
Scandium
Element number 9
Cl
Atomic Number

The number of
protons in the
nucleus of an atom
 Also tells us the
number of electrons
in an atom.
Find the atomic number of the
following:
1.
2.
3.
4.
5.
6.
Beryllium
Ne
Tin
As
Magnesium
W
On the Periodic Table..

Atomic number is written on the top left.

In the middle is the Chemical Symbol
(letter(s) that represent the type of atom)

Atomic mass is written on the bottom
How to use the numbers…

The number of
subatomic particles
in an atom can be
determined by
knowing the atomic
number and atomic
mass, and that there
is an important
difference in these
numbers.
How to find the 3 subatomic
particles:
1.
2.
Number of protons is equal to the
atomic number
Number of electrons is equal to the
atomic number

3.
Side note: In a neutral atom, the electrons
are always equal to the protons.
Number of neutrons is calculated by
subtracting the atomic number from the
atomic mass.
Example





Atomic number = 11
Atomic mass =
22.990
Protons = 11
Electrons = 11
Neutrons = 23
(22.990 rounded up)
– 11 = 12
Let’s try another…

Atomic number =

Atomic Mass =

Protons =

Electrons =

Neutrons =