Download The Periodic Table Notes

Objective 1. Students will name who first created the periodic table and
when it was created.
2. Students will describe the properties Mendeleev used to create
the periodic table.
3. Students will define atomic mass, atomic mass unit, and atomic
number.
4. Students will define valence electrons, proton number, and
neutron number.
5. Students will name and describe the groups/families of the
periodic table.
6. Students will use the periodic table to identify properties of
elements.
IV. The Periodic Table
a. Dmitri Mendeleev created the first periodic table in 1869. He
discovered that the elements shared certain patterns and trends. He
observed that the elements shared some chemical and physical
properties. Dmitri believed the properties that the elements shared
were important. Therefore, he wrote down all the properties he
knew about elements on cards. He used the properties of melting
point, density, color, atomic mass and bonding power to begin his
template. The atomic mass of an element is the average mass of one
atom of the element. The bonding power of an element refers to the
number of chemical bonds an element can form. This was
determined by how each element formed bonds with oxygen.
Mendeleev noticed that patterns appeared when the elements were
arranged in order of increasing atomic mass. As he put his cards in
order he realized that everything was not perfect and that there
appeared to be blanks. He predicted that the blanks were for
undiscovered elements and even described their properties.
Although today’s periodic table is arranged by atomic number, it was
due to Dmitri Mendeleev that we have a periodic table at all.
b. The periodic table displays characteristics of the elements, such as;
atomic mass, atomic number, element symbol, element name, proton
number and electron number. Since protons, neutrons and electrons
are so small, the atomic mass is measured using atomic mass units.
Atomic mass units measure the particles in an atom. The atomic
number, a unique property to each element, is the number of
protons in the nucleus of the atom.
c. Each atom has protons, neutrons, and electrons. Proton number is
equal to the atomic number. The neutron number is the amount of
neutrons in the nucleus in an atom. To find the neutron number of
an element, take the atomic number and subtract it from the atomic
mass. Atomic mass – atomic number = neutron number. Since
some atoms have different numbers of neutrons for the same
element the final number must be rounded up or rounded down.
While all atoms have electrons, the valence electrons are the most
important. Valence electrons are electrons found in the outermost
shell/level and are involved in chemical bonding. Valence electrons
are transferred or shared during chemical bonding.
d. A period is a row across the periodic table. Elements in the same
column of the periodic table are called a group or family. Each
family in the periodic table has its own characteristic properties
based on the number of valence electrons.
1. Group 1 is known as the alkali metal family. Alkali metals are
very reactive and each has only 1 valence electron.
2. Group 17 is known as the halogens. The halogens are very
reactive nonmetals and each has 7 valence electrons.
3. Group 18 is known as the noble gases. The noble gases are
considered inert which means they are not chemically reactive.
Except for helium (which has two), the noble gases have 8
valence electrons.