Transcript The Periodic Table

The Periodic Table
Unit II—Part 4
The Father of the Periodic Table—
Dmitri Mendeleev

Mendeleev (1834-1907) was the first
scientist to notice a relationship
between the elements
Around 1865 he arranged his periodic table
by atomic mass
 Said properties of unknown elements could
be predicted by the properties of elements
around the missing element

Dmitri Mendeleev
The Periodic Table

Henry Moseley
(1887-1915) later
discovered that the
periodic nature of
the elements was
associated with
atomic number, not
atomic mass.
The Periodic Table
Column = Group or
Family
18 columns on the
Periodic Table
Row = Period
7 rows on the
Periodic Table
What does the information in the
box tell me?
Atomic Number
= # of protons
and # of
electrons
Atomic Mass
= # of
protons plus
neutrons
1
H
1.008
Elemental
Symbol
Metals, Nonmetals, and
Hydrogen (H)
Metalloids
Nonmetals are on the
the only
nonmetal on the
metal side
Metals are to the
left of the
stair- step
Semi-metals,
“metalloids,”
touch the
stair-step
right of the stair-step
VALANCE ELECTRONS

The electrons that are in the outermost
energy level of any atom. Examples:
Hydrogen
has 1
valance
electron
Boron has 3
valance
electrons
Oxygen has
6 valance
electrons
Argon has 8 valance
electrons
8 VALANCE ELECTRONS

In order to feel and be
stable, all atoms would like
to have 8 valance electrons.
If they don’t already have 8
they will react very well and
bond with others that can
add up to 8. Example:
Oxygen has 6 valance
electrons and reacts very
easily with 2 Hydrogen
atoms to form H2O, water.
The Groups of the Periodic Table

Group 1 or 1a: The Alkali Metals
Most reactive metals on the PT
 Rarely found free in nature
 Charge of +1, 1 valence electron


Group 2 or 2a: The Alkaline Earth
Metals
Still quite reactive
 Charge of +2, 2 valence electrons

T he Groups of the Periodic Table

Groups 3-12 or 3-12b: Transition
Metals
Found freely and in compounds in nature
 Charge is usually +2 but can vary—usually 2
valence electrons


Group 13 or 3a: Boron Family

Charge is +3, 3 valence electrons
The Groups of the Periodic Table

Group 14 or 4a: The Carbon Family
Contains elements that can form unusual
bonds (carbon and silicon)
 Charge is +4 or -4, contains 4 valence
electrons


Group 15 or 5a: The Nitrogen Family

Charge is -3, contains 5 valence electrons
The Groups of the Periodic Table

Group 16 or 6a: The Oxygen Family
Also known as the chalcogens
 Charge is -2, 6 valence electrons


Group 17 or 7a: The Halogens
Most reactive nonmetals
 charge is -1, 7 valence electrons


Group 18 or 8a: The Noble Gases (The
Inert Gases)
Inert means Nonreactive, don’t normally
react with other elements
 Charge is 0, 2 or 8 valence electrons

Special Rows on the PT
Lanthanides
Actinides
We call these rare earth metals because
they are rarely found on earth.