Dmitri Mendeleev created the first periodic table in 1869 by organizing the known 63 elements based on their properties. He noticed patterns that allowed him to predict properties of undiscovered elements. The modern periodic table is arranged by atomic number with periods in horizontal rows and groups in vertical columns. It contains 117 known elements and illustrates patterns in their properties based on atomic structure.
3. PERIODIC TABLE
In 1869, a Russian Scientist, Dmitri Mendeleev created the very first Periodic
Table. He discovered a set of patterns that applied to all elements.
To start, Mendeleev wrote each of the discovered 63 elements. He organized
them based on their melting point, density, and color. He also included the element’s
atomic mass. Then he noticed a pattern and created the world’s first edition of what
we know today as the Periodic Table of Elements.
What is atomic mass? It is it the AVERAGE mass of all the isotopes of an
element. An isotope is an atom that has the same number of protons and a
different number of neutrons of atoms of the same element.
4. HOW IS THE PERIODIC
TABLE ARRANGED TODAY?
Periodic=regular, repeated pattern
Today’s table is arranged by atomic number
Periods are found in horizontal rows. There are seven total on the
table.
Groups are found in vertical rows. There are 18 families on the
Periodic Table.
There are 117 known elements found on the periodic table. (although
there is no #117).
5. HOW IS THE PERIODIC
TABLE ARRANGED TODAY?
The Alkali Metals are in Group #1 on the periodic table. Shade
them orange. They are very reactive and are always found in
combination with other elements.
The Alkaline Earth Metals are found in Group #2. Each is fairly
hard, gray-white and a good conductor of electricity. They are fairly
reactive although not as much as the Alkali Metals. Shade them in
yellow.
6. HOW IS THE PERIODIC
TABLE ARRANGED TODAY?
The Transition Metals are in groups #3-12. These include most of
the familiar metals such as iron, copper, nickel, silver and gold. Most
are hard and shiny and are good conductors of electricity. Shade these
in green.
In groups 13-15 on the Periodic table, only some elements are
metals. Most are not reactive—for example, aluminum, tin and lead.
Shade the metals in the “mixed groups” in light blue.
7. THE PERIODIC TABLE
TODAY
The first row of elements that sit below the Periodic Table are called
the Lanthanide series. They are located here to make the table more
compact. Lanthandes are soft, malleable and have a high conductivity.
Shade the Lanthanides pink.
The elements below the lanthanides are the actindes. Many of the
actinides are not found naturally in nature but made in a laboratory. Some
only last a fraction of a second. These elements (man-made) are called
“Synthetic elements.” Shade the actinide series red.
8. THE PERIODIC TABLE
TODAY
Non metals are elements that lack the properties of a metal. Most
non metals are poor conductors of electricity and heat and are
reactive with other elements. Solid non metals are dull and brittle.
Ten of the sixteen nonmetals are a gas at room temperature. Some
examples are Oxygen & Nitrogen.
Group #14 on the Periodic Table is the Carbon Family.
9. THE PERIODIC TABLE
TODAY
Group #15 is the Nitrogen family. It includes the elements Nitrogen,
Phosphorus, Arsenic, Antimony and Brismuth.
Group #16 is the Oxygen Family.
Group #17 is the Halogens— “salt-forming.” These elements
typically gains are shares one electron when it shares with other elements.
Group #18 are the Noble Gases. They are VERY unreactive and
were not discovered til the late 1800’s. Some examples include Helium,
Neon and Radon.
