1. U5: The History and Arrangement of the Periodic Table

3. I. History of the Periodic Table
1869 – Dmitri Mendeleev (Russian Chemist) thought elements may have something in common.
Made each element a card and listed its properties known at the time (mass, density, color, melting point and valence number).
Organized the elements into a table according to their atomic mass.

5. Dmitri Mendeleev – Columns = Groups/Families
Noticed a repeating pattern of valence electrons (1,2,3,4,5 etc..)
Noticed elements fell in to
columns (groups or families)
Noticed all elements in a column had the same valence electrons and showed similar physical and chemical properties.

6. Amazing Facts with his cards!
Mendeleev left blank spaces in his table so elements would line up – he also predicted what properties the undiscovered elements would have.
He predicted properties of five of these elements and their compounds. Three of these missing elements were discovered by others within 15 years.
The element, atomic number 101, has been named after Mendeleev.

7. Mendeleev’s Periodic Table by atomic mass (with empty spaces for elements that would soon be discovered)

8. Henry Moseley
1913 – Henry Moseley (English Scientist) changed the arrangement of the periodic table.
Instead of by increasing atomic mass , Moseley arranged the elements by increasing: atomic number (# of protons).
Interesting fact: Moseley's law = the energy of x-rays
emitted from an element is related to its atomic number.

9. II. Arrangement of the Periodic Table
Systematic arrangement of the elements by atomic number and chemical properties
Divided into Regions:
Metals, Nonmetals and Metalloids
Vertical Columns – Numbered groups/families
Horizontal Rows - Periods are by amount of energy levels (1-7) or orbital shells

10. III. REGIONS

11. Metals - location, properties
Elements on the left side of the table
Good conductors of electricity
Shiny
Ductile – can be drawn into thin wires
Malleable – can be hammered into thin sheets or shapes
High melting point
Tend to lose electrons

13. Nonmetals - location, properties
Elements on the right of the zigzag on the table
Do not conduct electricity or heat
Dull in appearance, not shiny
Brittle or break easily
Not Ductile or Malleable (cannot be drawn into wire or hammered into sheets)
Lower densities
Lower melting points
Tend to gain electrons or share electrons with each other

15. Metalloids - location, properties
Elements that are found along both sides of the zigzag line (except for Al)
Properties of both metals and nonmetals
Semiconductors - conduct heat and electricity better than nonmetals but not as well as metals
Solids
Can be shiny or dull
Both ductile and malleable

17. IV. Chemical Groups (Families)
Elements that are in the same group or family (column) of the Periodic Table have similar properties because they have the same number of valence electrons

18. Group (Family) 1 - Alkali Metals
Very reactive , bonds easily with other substances (unstable and explosive)
Never found alone in nature
Soft, silver-white, shiny
1 valence electron in outer energy level
Easily lose 1 electron to form a stable +1 ion
Forms ionic bonds

19. Think it Over:
Hydrogen is a nonmetal gas, and forms covalent bonds. So why is it in the Alkali Metal family?

20. Group/Family 2 - Alkaline Earth Metals
2nd most reactive elements, bond easily with other substances, unstable
Never found alone in nature
2 valence electrons in outer energy level
Loses 2 electrons to form stable +2 ions
Forms ionic bonds

21. Groups 3-12 The Transition Metals
Unpredictable
Common metals – gold, silver & copper
Can lose and/or share valence electrons
Forms Metallic Bonds

22. Rare Earth Elements (Inner Transition Metals)
First Row – Lanthanide Series
- naturally found rare Earth metals
- all but one is non-radioactive
Second Row – Actinide Series
- most are man-made and
most are radioactive
- many are short-lived

23. From Metals to Nonmetals
Group #
Name
Valence Electrons
Bonds
Region 13
Boron Family 3
Covalent
Ionic
(lose)
Metalloids & Metals 14
Carbon Family
Basis of Life 4
Metals, Metalloids Nonmetals

24. From Metals to Nonmetals
Group #
Name
Valence Electrons
Bonds
Region 15
Nitrogen 5
Covalent
Ionic (Gains)
Metals, Metalloids Nonmetals 16
Oxygen 6
Covalent or
Ionic (Gains
electrons)

25. From Metals to Nonmetals
Group #
Name
Valence Electrons
Bonds
Region 17
Halogen 7
Covalent or
Ionic
(Gains Electrons)
Nonmetals
Very
Reactive 18
Noble Gases or Inert Gases 8*
Does not bond
Stable
Non reactive
Full outer shells
* Helium has a full outer shell
with 2 valence electrons

26. Stability Groups 1-17 are unstable
The Noble Gas group/family is stable
Think it Over: What makes an element stable?

27. Point to Ponder
The element Carbon is the “Basis of Life”. What is meant by this?