The Periodic Table
Vocabulary and Notes
8th grade Science
Vocabulary
Physical property – observable characteristics of
matter without it changing into something else
(density, melting point)
Chemical property – observed when matter
interacts with other matter (flammability)
Atomic mass – average mass of 1 atom of an
element
Symbol –one or two letters that stand for an
element
Group – elements in a column in the Periodic
Table
Periods – horizontal row of the Periodic Table
History of Periodic Table
1830 – have 55 elements and no
idea of atomic numbers
Did feel that elements could be
organized in some manner
1860 –Dimitri Mendeleev
discovered system
Was a Russian scientist, wrote
facts about elements on cards
and organized cards
Noticed patterns appearing
when organization based on
increasing atomic mass
Portrait of Dimitri Mendeleyev by Ilya Repin
Organization
Atomic numbers increase from left to right and top
to bottom
Elements with same properties were placed in the
same group (vertical column) – also known as a
family
Family name based on first element in column
When placed in order of atomic mass and
properties didn’t match - new group created
Have 18 groups or vertical columns –numbered 1
thru 18
Left spaces if needed, confident that elements
would be discovered that fit group and properties
Organization cont.
Each horizontal row called a period
Have 7 periods – part of periods 6 & 7
have been separated out and appear
as rows below main section – keeps
table from being too wide
Can predict physical and chemical
properties based on where the
element is located on table
Periodic Table
Square in Periodic Table
20
Ca
calcium
40.08
Square for each
element usually
includes atomic
number, symbol,
name, and atomic
mass
Sometimes will
have other
information
depending on the
table
Let’s Look at Some Groups in the
Periodic Table
Metals
75% of elements
considered metals
Are good conductors
of electricity and heat
Are very reactive –
most form compounds
very easily by giving
up valence electron (s)
Easily combine to form
alloys
Are malleable and
ductile
Group 1 The Alkali Metals
Known as alkali metalsmost reactive family
Are soft, silver-gray, light
weight
Melting points decrease as
you go down the group
Melt at low temperatures
Have 1 electron in outer
shell which makes them
very reactive
When put in H2O some will
explode
Group 2 The Alkaline Earth Metals
2nd most reactive
group
Have 2 electrons in
outer shell – are
generally found
combined with other
elements
When mixed in a
solution will produce a
solution with ph > 7
This is why called
alkaline or base
metals
Transition Metals
Include a lot of
elements
Group has many
electrons and will
share them in many
ways
Able to put up to 32
electrons in second to
last shell- which is the
maximum
Able to use last 2
outer most shells for
bonding which makes
them have a wide
variety of properties
Group 7 Halogens
Have 7 electrons in
outer shell – makes
them as reactive as
alkali metals
Often bonds with
metals and
elements in group1
Less reactive as go
down the chart
Inert Gases
Called noble gases
Least reactive of all as
have full outer shells
Rarely combine with
other elements –
called inert
As you move down the
family gases become
rarer
Used all over world in
signs, balloons,
headlights, etc.
Lanthanides
Considered rare-earth metals
Found naturally on earth
Only one is radioactive
Actinides
All radioactive
Some not found in nature – are made only in high
tech laboratories and do not last very long
Two Special Cases
Hydrogen and Helium
Hydrogen
Most abundant element in
universe
Occurs as molecule of two
atoms – H2
A lot of Earth’s H found in
water (H20)
Is colorless, odorless,
tasteless gas
Low density
Is a nonmetal
Forms compounds with
many other elements
Not assigned to any group
Helium
Part of noble gases –but only
has 2 electrons in outer shell
2nd most abundant element on
Earth
Is rare due to atoms being so
light they escape from the
atmosphere
Is found where there is
natural gas (mostly in Texas)
Is twice as dense as H and is
nonflammable
Has lowest boiling point of any
substance and does not
freeze unless pressure is
applied
Lab Activity
The Missing Person
See hand-out
Additional Activities
Video - The Periodic Table
Activity - Fabulous Periodic Eggs
Lab – Understanding and Using the
Periodic Table
Activity - Element Scrabble
Worksheet – The Periodic Table
Element Cards
Web Quest
Credits
Textbook – Science Explorer Grade 8
Prentice Hall
Textbook – Chemistry – Molecule,
Matter, and Changes – Atkins, Peter
and Jones, Loretta
Website http://www.chem4kids.com/files/elem
_pertable.html