DO NOW TUESDAY
• Quietly sit down and begin work on your
Physical and Chemical Properties and
Changes quiz.
• When finished, turn your quiz in at the side
cart and pick up a half sheet of paper.
• Write everything you know about atoms on
this sheet.
•Today’s PLAN
–To differentiate between the subatomic particles of an atom:
protons, neutrons, and electrons.
–To explain the structure of the nucleus.
–To discuss what the atomic mass number and atomic number
represent concerning the atoms of an element.
•Todays DO
•We will complete foldables about the atom, atomic number, and
atomic mass number as notes to put in our binders.
•We will practice identifying the atomic number and atomic mass
number. Any practice that is not completed during class will be
HOMEWORK.
Atoms
Atoms
• Atoms are the basic building blocks of all
matter.
• EVERYTHING on Earth is made of
atoms…even the air and your body.
e-
Atoms are made of three particles:
e-
• Protons (+)
+N
+
+
N +N
• Neutrons (N)
e-
• Electrons (e-)
Electron
Proton
Neutron
Protons
• Protons
• Located in the nucleus
• Have a positive charge
• Have a mass of one
N
Neutrons
Neutrons
• Located in the nucleus
• Have no charge
• Have a mass of one –similar to the proton
N
N
N
Electrons
Electrons
e-
e-
• have a negative charge
• orbit the nucleus of the atom
• are very small (have basically NO
mass)
• in a neutral atom, there are the same
number of protons and electrons
Atom Structure
Neutron
-
Proton
Electron
+
+
-
What force holds all the parts of an
atom together?
• It is the electromagnetic force of attraction
between the positive protons in the nucleus
and the negative electrons orbiting around
the nucleus that holds the atom together.





Lets take a look deep
inside
Lets take a look deep
inside
Lets take a look deep
inside
Lets take a look deep
inside
+
+
This is a Proton.
+ Charge
Mass of ONE
Identifies the
atom
+
This is a Proton.
+ Charge
N
Mass of ONE
Identifies the
atom
+
This is a Proton.
+ Charge
N
Mass of ONE
Identifies the
atom
e+
This is a Proton.
+ Charge
N
This is a Neutron
No Charge
Mass of One
Mass of ONE
Identifies the
atom
This is an Electron.
- charge
e-
No Mass
+
This is a Proton.
+ Charge
N
This is a Neutron.
No Charge
Mass of ONE
Mass of ONE
Identifies the
atom
Atomic Number
Elements contain one or more of the same type of atom!
All known elements can be found on the periodic table.
• Elements can be identified by their atomic number.
• The atomic number is the number of PROTONS in the
atoms of an element.
• It can be used like a social security number for people.
• It is used to IDENTIFY the element from the
Periodic Table.
Example:
An element with 6 protons has an atomic number of 6 and is
the element Carbon from the Periodic Table.
Now You Try
• Identify the element and tell how many
protons it has:
1) Atomic number 7
Nitrogen: 7 protons
2) Atomic Number 20
Calcium: 20 protons
• Identify the element and give its atomic number.
3) 15 protons
4) 4 protons
Phosphorus: Atomic number 15
Helium: Atomic Number 4
• Give the atomic number and number of protons.
5) Argon
Atomic number 18; 18 protons
6) Sulfur
Atomic number 16; 16 protons
Atomic Mass Number
• The atomic mass number includes the
number of protons and neutrons, since they
are the two largest particles in the atom.
• Since they are both located in the nucleus,
the mass of the atom is located
in the nucleus.
Atomic Mass Number = protons +
neutrons
Using the Periodic Table
Using the Periodic Table
2
Using the Periodic Table
2
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
2
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
2
He
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
2
He
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
Element symbolgives the name of the
element.
2
He
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
Element symbolgives the name of the
element.
2
He
4
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
Element symbolgives the name of the
element.
2
He
4
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
Element symbolgives the name of the
element.
Atomic mass numberThe number of
protons + neutrons.
2
He
4
Using the Periodic Table
Atomic Numberidentifies the element.
(also the number of
protons)
Element symbolgives the name of the
element.
Atomic mass numberThe number of
protons + neutrons.
2
He
4
Now You Try
For the following pictures, give the name of the element, its atomic
number, number of protons, and atomic mass number.
Beryllium
Atomic number 4
4 protons
Atomic mass number 9
Sodium
Atomic number 11
11 protons
Atomic mass number 23
Oxygen
Atomic number 8
8 protons
Atomic Mass Number 16
Compounds contain more than one type of atom!
Example of organic compound (a compound with carbon and
hydrogen atoms):
 Methane (natural gas) – CH4 (1 atom of carbon and
four atoms of hydrogen)
Example of inorganic compound (a compound without carbon
and hydrogen atoms):
 Water – H2O (2 atoms of hydrogen and one atom of oxygen)
-
+
An ion is an atom or group of atoms with a positive or negative
charge!!
 A particle with a neutral charge has the same number of
protons and electrons.
 An ion does not have the same number of electrons and protons.
 Examples of ions:
• H+ - A hydrogen atom that is missing one electron.
The atom has one more proton than electron,
and must have a positive charge.
•CO32- - Carbonate has two more electrons than protons