Periodic Table
A Closer Look
History of the Periodic Table

Mendeleev arranged
the elements into the
world’s 1st periodic
table


Increasing atomic
mass
Atomic mass was
known by comparing
the amounts of
elements that reacted
with each other
Modern Periodic Table


Not identical to
Mendeleev’s table –
he didn’t know about
protons and electrons
Increasing atomic
number instead of
mass


Number of protons
Number of electrons
Groups


Columns on the table
Same number of
valence electrons



Similar chemical
properties
Similar physical
properties
More reactive as you
go down in a group
Group 1 – Alkali metals
Stored in oil so they won’t react with the air
Valence Electrons




Outermost electrons
They participate in all
chemical bonds
Every atom “wants”
eight valence
electrons
Noble gases already
have eight valence
electrons – least
reactive elements
Groups







Numbered left to right
Group 1 – alkali metals
Group 2 – alkaline earth metals
Groups 3 to 12 – transition
metals
Groups 13 to 16 – metals,
metalloids, & nonmetals
Group 17 – halogens
Group 18 – noble gases
Group 3

Scandium

Lanthanum

Yttrium

Actinium
Periods




Horizontal rows
The two at the bottom
are part of rows 6 & 7
Same number of
energy levels
Properties change in
the same way across
each row (periodic
law)
Period 3

Lithium

Beryllium

Boron

Carbon

Nitrogen

Oxygen

Fluorine

Neon
General Categories



Metals

Shiny

Conductors

Ductile

Malleable
Nonmetals

Dull

Insultators

Brittle
Metalloids

Properties of both
Placement on the Periodic Table
Metalloids
Metals
Nonmetals
Period 4, Group 1
contains K, which
is potassium
Properties of Metals
Shiny
Conductors
Ductile
Malleable
Metallic Elements

Metallic properties
increase as you
move down and to
the left

Most metallic
elements are in
group 1
Alkali Metals

Group 1
Li
 Na
K
 Rb
 Cs
 Fr

Very reactive




Easily lose one
valence electron
The further out the
electron is from the
nucleus the easier it is
to lose it
Reactivity increases
as you go down in the
group
Alkaline Earth Metals

Group 2
Be
 Mg
 Ca
 Sr
 Ba
 Ra

Properties of Alkaline Earth Metals

Less reactive than
alkali metals
Don’t reactive as
violently with water
 Need more energy
to begin their
reactions


Lose two valence
electrons
Transition Metals
Groups 3 to 12
 AKA “heavy metals”



Large nuclei
Form colored compounds
Alloys

Homogeneous mixture of metals

Mix together metals to get the exact properties you
want

Instruments, jewelry, construction, etc.

Sterling silver, brass, bronze, steel
Coinage Metals
Resistant to
corrosion
 Expensive
 Found in pure form
 Three –

Copper
 Silver
 Gold

Rare Earth Metals
Long Periodic Table
This is too long for practical use, so we pull the two
rows out and put them at the bottom of the table.
Transuranium Elements

Elements past
uranium

Atomic numbers
higher than 92

Radioactive

Very short half lives
 Not
found in nature
 Created
in laboratories
Radioactivity
One element turning into another element
 Half life = how fast the element changes

Metalloids
This line separates
the metals from the
nonmetals on the
periodic table
These are the
metalloids
•B
•Si
•Ge
• As
•Sb
•Te
•Po
Semiconductors
Metalloids
 Only let electricity
through in one
direction
 Used in modern
electronics

Cell phones
 Video games
 Computer chips

Organic Compounds
Historically
believed to be
created only by
living organisms
 Contain carbon,
hydrogen, oxygen,
nitrogen and sulfur

Chocolate
Nonmetallic Elements
Insultators
Brittle
Dull
Halogens

Group 17
F
 Cl
 Br
I

“Salt forming”
 Most reactive
nonmetals

Reactivity of Halogens

Combine with
metals to form
compounds called
salts
Sodium chloride
 Magnesium iodide


Fluorine is the
most reactive
element on Earth
Noble Gases

Group 18
He
 Ne
 Ar


Kr
 Xe
 Rn

Eight valence
electrons, so
they don’t react
with anything