1. Intro To The Periodic Table

2. How Was The Periodic Table Created?
Throughout history elements were discovered at different times but they were not put in any order to classify them.
By 1828, 53 elements were discovered.
To bring ORDER out of CHAOS, to classify is a basic need of man. Therefore, scientists began looking for similarities among the elements as more were continuing to be discovered.

4. Who Is Dmitri Mendeleev?
In 1871, Russian scientist Dmitri Mendeleev organized the known elements of the time according to increasing atomic mass.
He left spaces on the periodic table where elements were yet to be discovered.
Mendeleev also recognized that certain similarities in the chemical properties of elements occurred at regular intervals. He implemented John Newland’s law of octaves.
 Law of Octaves – every 8 elements tend to have the same chemical properties (groups 1-2 and on your periodic table)

5. 26 Fe
55.845 28 Ni 27 Co
Mendeleev 51 Sb 53 I 52 Te
127.60

6. Who Is Henry Moseley?
In 1911 English scientist Henry Moseley discovered that the elements on the periodic table fit into patterns better when they are arranged in order of increasing atomic number, or the number of protons in the nucleus.
Moseley’s periodic table represents the periodic law which is what we follow when we study chemistry today.
Periodic Law - the physical and chemical properties of the elements are periodic functions of their atomic numbers
*When elements are arranged in order of increasing atomic number, elements with similar properties occur at regular intervals.

7. 26 Fe
55.845 27 Co 28 Ni
Moseley 51 Sb 52 Te
127.60 53 I

8. Organization Of The Periodic Table

9. How are the Elements Classified?
Elements can be classified as metals, nonmetals, or metalloids (semimetals).
Metals
Nonmetals
Metalloids (Semimetals)
Located to the left of the staircase on the periodic table
Tend to lose electrons and form positive (+) ions to look like a noble gas
Have a shiny appearance (luster)
Good conductors of electricity
Located to the right of the staircase on the periodic table
Tend to gain electrons and form negative (-) ions to look like a noble gas
Dull in appearance
Poor conductors of electricity
Located along the staircase on the periodic table
May form + or – ions gas OR share electrons to look like a noble gas
Appearance varies
Intermediate conductor of electricity

10. Allotropes Elements that exist in more than one form.
The atoms of that element are bonded together in a different manner.
Carbon has 2 common allotropic forms.
Diamond
Graphite