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

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

3. Dmitri Mendeleev (cont.)
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Dmitri Mendeleev (cont.)
Mendeleev organized each card (element) according to its atomic mass
Noticed a repeating pattern of valence numbers (1, 2, 3, 4, 5, etc.)
Noticed elements fell into columns (groups or families)
Noticed all elements in a column had the same valence number and showed similar physical and chemical properties.

4. Dmitri Mendeleev (cont.)
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Dmitri Mendeleev (cont.)
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.

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Henry Moseley
1913 – Henry Moseley (English Scientist) changed the arrangement of the periodic table.
Instead of by increasing atomic mass, it was arranged by increasing atomic number (# of protons).

7. Arrangement of the Periodic Table
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Arrangement of the Periodic Table
Systematic arrangement of the elements
Arranged by atomic number and properties
Numbered groups/families are in vertical columns
Periods are by amount of energy levels in horizontal rows (1-7)
Divided into regions: metals, nonmetals and metalloids

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9. Metals - 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 and other shapes
High melting point
Tend to lose electrons

10. Nonmetals - properties
Elements to the right of the zigzag on the table
Do not conduct heat or electricity
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

11. Metalloids - 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

12. Chemical Groups (Families)
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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

13. Group (Family) 1 - Alkali Metals
1 valence electron in outer energy level
Very reactive, bond easily with other substances (unstable and explosive)
Never found alone in nature
Soft, silver-white, shiny
Easily lose 1 electron to
form a stable +1 ion
Form ionic bonds
Note:
Hydrogen is a nonmetal gas, and forms covalent bonds. So why is it in this Alkali Metal family?

14. Hydrogen is a nonmetal gas and forms covalent bonds
Hydrogen is a nonmetal gas and forms covalent bonds So why is it in the Alkali Metal family?
The number of valence electrons = 1

15. Group/Family 2 - Alkaline Earth Metals
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Group/Family 2 - Alkaline Earth Metals
2 valence electrons in outer energy level
2nd most reactive elements, bond easily with other substances, unstable
Never found alone in nature
Lose 2 electrons to form stable +2 ions
Form ionic bonds
Combine with oxygen and other non-metals in the Earth’s crust

16. Groups 3-12 The Transition Metals
1 or 2 valence electrons
Can lose and/or share valence electrons
Common metals – gold, silver & copper
Form metallic bonds
Unpredictable

17. From Metals to Nonmetals (e- in outer energy level)
Group 13 Boron Group/Family 3 valence electrons
Group 14 Carbon Group 4 valence electrons
Group 15 Nitrogen Group 5 valence electrons
Group 16 Oxygen Group 6 valence electrons
Group 17 Halogen Group 7 valence electrons
Group 18 Noble Gases 8 valence electrons
* Helium is a Noble Gas but has a full outer shell with 2 valence e-

18. Rare Earth Elements (Inner Transition Metals)
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Rare Earth Elements (Inner Transition Metals)
First Row –Lanthanide Series
- Rare Earth metals
- All but one is non-radioactive
Second Row – Actinide Series
- Most are man-made and radioactive
- Many are short-lived