Introduction to
The Periodic
Table
Why is the Periodic Table
important to us?
• The Periodic Table
is the most useful
tool to a chemist.
• You get to use it on
every test.
• It organizes lots of
information about
all the known
elements.
Periodic Table
There are 92 naturally occurring elements arranged by atom size.
Periodic table
The atoms are arranged by size from smallest (H) to largest.
Elements are arranged:
Vertically into Groups
Horizontally Into Periods
We’ll learn later
how this
organization works.
Hydrogen is the smallest atom.
• Hydrogen has an
atomic number of 1.
• Hydrogen belongs to
a family of its own.
Reading the Periodic Table
Each box on the Periodic Table
stands for 1 of the elements.
6
C
CARBON
12
If you have no trouble
reading the above
information off the Chart,
click here to skip the
sample problems.
The atomic number for the element.
The symbol for the element.
The name of the element.
The atomic mass for the element.
We can get 4 pieces of
information from that box.
Reading the Table: Symbols
Using your Periodic Table, answer these:
What is the chemical symbol for:
• Sulfur?
S
• Neon?
Ne
Answer all, and then click for the answers.
Reading the Table: Symbols
Using your Periodic Table, answer these:
What elements have these chemical symbols:
• Ag?
Silver
• Na?
Sodium
Answer all, and then click for the answers.
Reading the Table: Atomic
Numbers
Using your Periodic Table, answer these:
What elements have these Atomic Numbers:
• 9?
Fluorine
• 56?
Barium
Answer all, and then click for the answers.
Let’s Review!
• Every one of these
elements is made of the
same particles.
• A Hydrogen proton is
identical to Gold protons.
• What makes atoms
different is the number of
protons.
• The Atomic Number gives
us the number of protons.
Atomic Number
The Atomic Number
gives us the number
of protons and
electrons.
2.
1.Sodium
Helium
has
has
anan
atomic
atomic
number
numberof
of11.
2. How
How many
many
electrons
protons does
doesitithave?
have?
Use your copy of the Periodic
Table for the rest of this activity.
11
2
Atomic Number
The Atomic Number
gives us the number
of protons and
electrons.
1. What
2.
What
element
element
has
has
9215
protons?
electrons?
Let’s try the same
problems in reverse.
Phosphorus
Uranium
Mass Number
The Mass Number is the sum of the number
of protons and the number of neutrons.
Mass Number = Protons + Neutrons
What is the mass number of an element that has 17 protons
What
element is it?
and 18 neutrons?
Hint:
the formula
Hint:Use
Look
at theabove.
Periodic
Table.
Chlorine
35
Mass Number
Many Periodic Tables will use the atomic mass or atomic weight
instead of the mass number. I know it sounds confusing, but they
are really the same thing as the mass number.
When using these Periodic Tables, you will have to round the
atomic mass off to get the mass number.
8
The atomic mass for oxygen is 15.9994.
O
OXYGEN
15.9994
We round off 15.9994 to 16. Thus 16 is
the mass number of oxygen.
Finding the Number of Neutrons
The Mass Number is the sum of the number
of protons and the number of neutrons.
Mass Number = Protons + Neutrons
Neutrons = Mass Number - Protons
1. How
2.
How
many
many
neutrons
neutrons
does
does
Sulfur have?
Aluminum
have?
14
16
Finding the Number of Neutrons
If you got those two questions right, click
here to go to the next slide.
If you had trouble, click elsewhere on the
slide to continue.
2. How many neutrons does
Aluminum have?
14
Step
Step
3: 2:
1:
How
or
Find
Calculate
what
many
the
is 27
Atomic
neutrons
the
– 13?
number
Number
added
of protons.
and
to 13Mass.
would make 27?
Aluminum
hasThe
13
protons
because
thatMass
is the - 27
Answer
is
Atomic
Number
– 13
Atomic
Atomic
Number.
14 neutrons.
Review
Questions
Begin
Review Question
#1
Which element
has the smallest
atom?
• Helium
• Hydrogen
• Oxygen
• Nitrogen
Answer: Hydrogen (H)
Review Question
#2
Which element
has an atomic
number smaller
than Aluminum?
• Uranium
• Iron (Fe)
• Sodium (Na)
• Chlorine
Answer: Sodium (Na)
Review Question
#3
Which element
has an atomic
number greater
than Iron (Fe)?
• Uranium
• Lithium
• Sodium (Na)
• Chlorine
Answer: Uranium
Review Question
#4
Which element has
a nucleus with 13
protons?
• Calcium
• Aluminum
• Silicon
• Iron
Answer: Aluminum
Review Question
#5
How many protons,
electrons, and
neutrons does
Hydrogen have?
Answer:
Protons – 1
Electrons – 1
Neutrons - 0
Review Question
#6
How many protons,
electrons, and
neutrons does
Phosphorus have?
Answer:
Protons – 15
Electrons – 15
Neutrons - 16
Review Question
#7
How many protons,
electrons, and
neutrons does
Argon have?
Answer:
Protons – 18
Electrons – 18
Neutrons - 22
Review Question
#8
How many protons,
electrons, and
neutrons does
Uranium have?
Answer:
Protons – 92
Electrons – 92
Neutrons - 146
Go back to the main page,
and
open the
“Constructing an Atom”
PowerPoint.