1. History of the Periodic Table
1790s Antoine Lavoisier compiled a
list of the 23 known elements
1864 John Newlands named the periodic relationship that he observed in chemical properties the
“Law of the Octaves”

2. Demetri Mendeleev
Demonstrated a connection between atomic mass and elemental properties.
Organized the first Periodic Table of the Elements
Predicted the existence and properties of undiscovered elements
Arranged his Periodic Table according to increasing ATOMIC MASSES of the elements

3. In 1870 there were about 70 known elements

4. In 1911 Henry Moseley
Discovered that atoms of each element contain a unique number of protons in their nucleus
Arranged the elements in increasing ATOMIC NUMBER rather than atomic masses as Mendeleev had done

5. Periodicity- A repeating pattern
Periodic Law- States that the chemical and physical properties of elements are periodic functions of their atomic number
Periodic Table- A chart organizing elements by their INCREASING atomic number.

6. FAMILIES YOU MUST KNOW Family # 1- Alkali Metals Family,
Lithium – Francium (Li-Fr)
excluding Hydrogen because it is
NOT a metal. Hydrogen is a gas!
Family #2- Alkaline Earth Metals, (Be – Ra)

7. Family # 17- The Halogens
Fluorine – Astatine (F– At)
Family # 18- The Noble Gases
Helium – Radon
Transition Metals – Families 3 – 12
the “d” block

8. Periods 6 and 7 Lanthanides “Rare Earth Metals”, used in TV
Period Elements # 58 –71
Very Colorful
Actinides Radioactive elements
Period 7
Most are synthetic or man-made

9. Representative Elements
Elements within the “s” and the “p” blocks

10. ZIG-ZAG LINE The zig-zag line separates the metals from the non metals
Metals on the left of the zig-zag line
Non metals to the right of the zig-zag line

11. Metalloids
Metalloids are elements located next to the zig-zag line with the
EXCEPTION OF ALUMINUM
Metalloids include the following:
Boron, B Arsenic, As
Silicon, Si Antimony, Sb
Germanium, Ge Telurium, Te
Polonium, Po

12. Metalloids exhibit properties of both metals and non metals
- They are somewhat poor conductors
- called semi conductors
- used in computers, cell phones, etc.