1. How the Elements are Organized
The Periodic table
How the Elements are Organized

2. John Newlands
Arranged the known elements according to their properties and in order of increasing atomic mass
He placed the elements in a table

3. Law of Octaves The pattern discovered by John Newlands
All elements in a given row had similar chemical and physical properties and these properties seemed to repeat every eight elements

4. Dmitri Mendeleev
1869, produced the first orderly arrangement of elements in the periodic table
Elements are arranged in order of increasing atomic mass
He even predicted elements that had not been discovered yet

5. Henry Mosely
Changed the periodic table to be organized by atomic number instead of atomic mass

6. Periodic Law
States that when the elements are arranged according to their atomic numbers, elements with similar properties appear at regular intervals

7. Valence Electrons
Elements in each column of the periodic table have the same number of electrons in their outer energy level (valence electrons)
It is the valence electrons of an atom that participate in chemical reactions with other atoms, so atoms with the some number of valence electrons tend to react in similar ways

8. Groups A vertical column on the periodic table
Elements in the far left column have 1 valence electron
Elements in the far right column have 8 valence electrons

9. Period A horizontal row on the periodic table
Elements in the same period have the same number of occupied energy levels

10. Main Group Elements In the s and p blocks of the periodic table
The configuration of their valence electrons can be written as ns2
Sometimes called the representative elements because they have a wide range of properties

11. Periodic Table organization

12. Alkali Metals- Group 1
Are metals that react with water to make alkaline solutions
Ex.-Potassium reacts vigorously with cold water to form hydrogen gas and the compound potassium hydroxide, KOH
Have a single valence electron, very reactive
When they lose the valence electron they become stable

13. Alkali Metals, cont. Stored in oil
Never found in nature as pure substances, but only as compounds (such as NaCl)
Soft metals
Good conductors of electricity

14. Alkali Metals
Potassium
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15. Alkaline-Earth Metals
Highly reactive, found as compounds rather than pure elements
Slightly less reactive than the alkali metals
Have two valence electrons and must lose both to get a stable electron configuration
Harder and have higher melting points that alkali metals

16. Halogens-Group 17
The most reactive group of nonmetal elements because of their 7 valence electrons, only need 1 electron for a stable configuration
Often react with alkali metals which only have one valence electron
React with most metals to form salt (Halogen means “salt maker”)

17. Noble Gases- Group 18 Unreactive, have a full set of valence electrons
Except for helium they all have an outer shell configuration of ns2np6 (n is the period number)

18. Hydrogen Most common element in the universe
Consists of just one proton and one electron
Behaves unlike any other element
Can react with many other elements, including oxygen

20. Metals Make up the majority of elements Shiny Conduct electricity
Ductile-can be squeezed into a wire
Malleable- can be hammered or rolled into sheets