Lecture 6.1- The Periodic Table

Chemists use the properties
of elements to sort them into
groups.

Chlorine, bromine, and iodine have
very similar chemical properties.

Mendeleev arranged the elements in
his periodic table in order of
increasing atomic mass.
Mendeleev’s
periodic table was
used to predict
the properties of
undiscovered
elements.

An Early Version of Mendeleev’s Periodic Table

In the modern periodic table,
elements are arranged in order
of increasing atomic number.

The periodic law: When elements are
arranged in order of increasing atomic
number, there is a periodic repetition of
their physical and chemical properties.
–The properties of the elements within a
period change as you move across a
period from left to right.
–The pattern of properties within a period
repeats as you move from one period to

The stair-step line divides the
metals from the nonmetals.

Any square with a side on the stair-
step line is a metalloid (semi-metal),
EXCEPT ALUMINUM.

Any square with a side on the stair-
step line is a metalloid (semi-metal),
EXCEPT ALUMINUM.
Across a period, the properties of elements
become less metallic and more nonmetallic.

Metals

Nonmetals

Metalloids (semi-metals)

Metals are good conductors of heat
and electric current.
–80% of elements are metals.
–Metals have a high luster, are
ductile, and are malleable.
–Metals tend to lose electrons.

6.1
Uses of Iron, Copper, and Aluminum

6.1
Uses of Iron, Copper, and Aluminum

6.1
Uses of Iron, Copper, and Aluminum

In general, nonmetals are poor
conductors of heat and electric
current.
–Non-metals tend to gain e-
–Most nonmetals are gases at room
temperature.
–A few nonmetals are solids, like sulfur,
carbon, and phosphorus.

A metalloid generally has
properties that are similar to those
of metals and nonmetals.
•Also called semi-metals
The behavior of a metalloid can be
controlled by changing conditions.

If a small amount of boron is mixed with
silicon, the mixture is a good conductor of
electric current. Silicon can be cut into
wafers, and used to make computer chips.

The periodic table displays the symbols
and names of the elements, along with
information about the structure of their
atoms.

Groups are labeled 1-18 or 1A-8A

The Group 1A elements are called
alkali metals.

In their elemental form alkali metals
are extremely reactive, so they are not
naturally found in elemental form.
search youtube for brainiac alkali metal to watch this video at home

In their elemental form alkali metals
are extremely reactive, so they are not
naturally found in elemental form.
search youtube for brainiac alkali metal to watch this video at home

The Group 2A elements are
called alkaline earth metals.

The nonmetals of Group 7A
are called halogens.

The noble gases are the elements
in Group 8A of the periodic table.

The blimp contains
helium, one of the
noble gases.

The Representative Elements
Elements in groups 1A through 7A are
often referred to as representative elements
because they display a wide range of
physical and chemical properties.

6.2
Representative Elements

6.2
Representative Elements

6.2
Representative Elements

6.2
Representative Elements

Transition metals

Transition metals
Inner
transition
metals