ATOMS
What are elements made of?
What makes up ALL matter?
ATOMS!!
Draw a circle
on your
paper.
You have 2
minutes to write
down everything
you know about
atoms!
An atom is the smallest particle into
which an element can be divided and
still be the same substance.
Aluminum
atoms seen
through a
scanning
tunneling
electron
microscope.
What are atoms made of?
• Atoms can be divided into smaller parts called
subatomic particles.
1.Nucleus
2.Electron
3.Proton
4.Neutron
5.Electron Cloud
Protons
• Protons are positively charged
particles in the nucleus.
+
Neutrons
• Neutrons are particles in the nucleus that
have no electrical charge.
• Neutrons are a little bigger than protons.
O
No
Charge!
Nucleus
• Every atom has
a nucleus, a
positively
charged center
portion.
Inside the Nucleus
• Both protons and neutrons are found
inside the nucleus of an atom.
Outside the Nucleus
• Electrons are the negatively charged
particles in atoms.
_
Electrons are found around the
nucleus within electron clouds.
• An atom has the same number
of protons as electrons.
This Lithium atom
has 3 protons and
3 neutrons.
• If a hydrogen atom has 1 proton, how
many electrons does it have?
• If a nitrogen atom has 7 protons, how
many electrons does it have?
What Makes Elements Different?
• Atoms make up individual elements.
By changing the number of protons
in the atom, you change the type of
element.
Protons and Electrons are in ALL atoms!
• The simplest atom is made up of just one of each.
1. Draw one proton in the
center of the atom
(nucleus).
2. Put one electron in the
electron cloud.
3. You just drew a
hydrogen atom!
-
+
All other atoms have protons, neutrons,
and electrons.
1. Draw two protons in the
center of the atom
(nucleus).
2. Put two neutrons in
the nucleus.
3. Put two electrons in
the electron cloud.
4. You just drew a helium
atom!
-
+
-
+
Atomic Number
• The atomic number is the number of
protons in the nucleus of an atom.
This Lithium atom has 3
protons, so it has an
atomic number of 3.
• Every hydrogen atom has only one proton in
its nucleus, so hydrogen has an atomic
number of 1.
• Every carbon atom has six protons in its
nucleus, so carbon has an atomic number of 6.
Your turn…
How many protons are in the nucleus of the
following elements?
1.
2.
3.
4.
Atomic Mass
• The atomic mass is the sum of
the protons and neutrons in an
atom.
PROTONS + NEUTRONS = ATOMIC MASS
We can determine the atomic mass of an
element by looking at the periodic
table.
Hydrogen has an
atomic mass of
1.00794
Your turn…
How many protons and neutrons are in the
nucleus of the following elements?
1.
2.
3.
4.
Number of Neutrons?
Let’s Look Closer at Electron Clouds
• There are some rules for drawing atoms:
placing electrons in the electron clouds.
Your Turn!
Atomic Number
1.
Atomic Mass
2.
Atomic Mass
3.
Atomic Number
4.
Atomic Mass
5.
Atomic Number
6.