Elements & Atoms
An atom refresher
• Matter is anything that takes up space and has
mass.
• All matter is made of atoms
• Atoms are the building blocks of matter, sort of
how bricks are the building blocks of houses.
An atom has subatomic particles
• An atom has three parts:
• Proton = positive
• Neutron = no charge
• Electron = negative
The proton & neutron are
found in the center of the
atom, a place called the
nucleus.
• Electrons revolve around
nucleus in shells or energy
levels.
• The electrons in the outer
most shell of any element
are called valance
electrons.
Activity: Use periodic table to complete the
table. Worksheet on SEQTA
Atomi Atomi Elemen Elemen #Proton #Electron #Neutron
Electron
c#
c
t Name
t
s
s
s
Configuratio
Mass
Symbo
(+)
(-)
(0)
n
l
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
10
10
10
Neutral Atom
• In a neutral atom, the
number of protons equals
the number of electrons,
so the overall charge is
zero (0)
• Example/ Helium, with an
atomic number of 2, has
2 protons and 2 electrons
when stable
Ions
• Sometimes atoms will
gain or lose electrons
and form IONS
• Because an electron has
a negative charge:
• When an atom GAINS
electrons it becomes
NEGATIVE
• When an atom LOSES
electrons it becomes
POSITIVE
Periodic Table
Atomic Number:
Number of protons
and it is also the
number of electrons
in an atom of an
element.
Elements Name
Atomic Mass/Weight:
8
O
Oxygen
16
Number of protons +
neutrons.
Draw atomic structure of Oxygen in
your books and label it
Nucleus
1st shell
2nd shell
3rd shell
So let’s try it---• How to draw a Lithium atom
• First, look at the Periodic Table
• Second, determine the number of
protons (Look @ the atomic
number)
• Then determine the number of
neutrons (Atomic mass – atomic
number)
• Then determine the number of
electrons (Look @ the atomic
number)
3
Li
Lithium
7
So let’s try it….
Protons = 3
3
-
Li
+
+
+
-
Lithium
-
Electrons = 3
2 in the 1st shell, 1 in the 2nd shell
7
Neutrons = 4
(7-3=4)
Your activity…
• Draw atomic structure of following atoms in
your books and label protons, neutron, nucleus
and electrons.
• Hydrogen
• Carbon
• Chlorine
• Sodium
• Potassium
Your activity…
• Use periodic table to identify the following
atoms using atomic number.
Your activity…
• Use periodic table to write electronic
configuration of
• Worksheet Electronic Structure of the First
20 Elements