1. The History of the Modern Periodic Table

2. Johann Dobereiner Model of triads 1780 - 1849
In 1829, he classified some elements into groups of three, which he called triads. They had similar chemical and physical properties.
(ex. Cl, Br, I and Ca, Sr, Ba)
Model of triads

3. John Newlands Law of Octaves 1838 - 1898
In 1863, he suggested that elements be arranged in “octaves” because he noticed that certain properties repeated every 8th element.
Law of Octaves

4. John Newlands 1838 - 1898 Law of Octaves
Newlands' claim to see a repeating pattern was met with savage ridicule on its announcement. His classification of the elements, he was told, was as arbitrary as putting them in alphabetical order and his paper was rejected for publication by the Chemical Society.
Law of Octaves

5. Dmitri Mendeleev
In 1869 he published a table of the elements organized by increasing atomic mass.

6. Lothar Meyer
At the same time, he published his own table of the elements organized by increasing atomic mass.

7. Elements known at this time

8. Mendeleev...
stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U)
was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown.

9. After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev’s predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.

10. However, in spite of Mendeleev’s great achievement, problems arose when new elements were discovered and more accurate atomic weights determined. By looking at our modern periodic table, can you identify what problems might have caused chemists a headache?
Ar and K
Co and Ni
Te and I
Th and Pa

11. Henry Moseley
In 1913, he rearranged the elements in order of increasing atomic number.
“There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

12. Henry Moseley
His research was halted when the British government sent him to serve as a foot soldier in WWI. He was killed in the fighting in Gallipoli by a sniper’s bullet, at the age of 28. Because of this loss, the British government later restricted its scientists to noncombatant duties during WWII.

13. Glenn T. Seaborg
After co-discovering 10 new elements, in 1944 he moved 14 elements out of the main body of the periodic table to their current location below the Lanthanide series. These became known as the Actinide series.

14. Glenn T. Seaborg
He is the only person to have an element named after him while still alive.
"This is the greatest honor ever bestowed upon me - even better, I think, than winning the Nobel Prize."

15. Periodic Table Geography

16. The horizontal rows of the periodic table are called PERIODS.

17. Period numbers correspond to the highest occupied energy level.
Horizontal rows are
called periods

18. The elements in any group of the periodic table have similar physical and chemical properties!
The vertical columns of the periodic table are called GROUPS, or FAMILIES.

19. The chemical behavior and properties of elements in a family are associated with the electron configuration of its elements.
For A family elements the valence electron configuration is the same in each column.

20. With the exception of helium which has a filled s orbital, the nobles gases have filled p orbitals.

21. The elements of a family have the same outermost electron configuration except that the electrons are in different energy levels.
The group numbers for the representative elements are equal to the total number of outermost electrons in the atoms of the group.
10.17

22. Periodic Law
When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

23. Elements in the A groups are designated representative elements

25. Properties of Metals
Metals are good conductors of heat and electricity.
are shiny
are ductile (can be stretched into thin wires).
are malleable (can be pounded into thin sheets).
Its reaction with water results in corrosion.

26. Properties of Non-Metals
Non-metals are poor conductors of heat and electricity.
are brittle and break easily.
They are dull.
Many are gases.
Sulfur

27. Properties of Metalloids
Metalloids (metal-like) have properties of both metals and non-metals.
They are: Boron, Silicon, germanium, arsenic, antimony, tellurium, astatine
Silicon

28. Alkali Metals

29. Alkaline Earth Metals

30. Transition Metals

31. InnerTransition Metals
These elements are also called the rare-earth elements.
InnerTransition Metals

32. Halogens

33. Noble Gases

34. Classwork: color code periodic table
Include: metals, nonmetals, metalloids, alkali metals, alkaline- earth metals, halogens, noble gases, transition metals, inner transition metals

35. Reading the Periodic Table
Metalloids
Appearance will vary
3 to 7 valence electrons
Form positive and/or negative ions
Conduct better than nonmetals but nor as well as metals
Properties of metals and nonmetals
Often used in semi-conductors for computer chips
Separate metals from nonmetals; touching bold stair-step line
They are: Boron, Silicon, germanium, arsenic, antimony, tellurium, astatine
Aluminum is a metal.

36. Categories of the Periodic Table
Metals – (specific)
*Reactive metals (alkali and alkaline earth metals)-
-Alkaline earth metals- very reactive and are found in the earth’s crust.
-Alkali metals- soft and malleable & ductile ( bendable and can be reshaped)
*Transition metals (includes poor metals)-
less reactive than most metals
found in foods we eat, for industry (steel, copper), modern technology catalytic converters, and incandescent light bulbs), and alloys (steel and brass).
*poor metals- soft, low melting points, ex: lead
*Rare earth metals (lanthanide series and actinide series)-
-previously believed to be rare, however as mining improved, scientist realized that they are not rare, just hard to isolate.

37. Reading the Periodic Table
NonMetals
*Noble gases- Group 18, almost never react with other elements
-Some are used to make colorful lights
*Halogens- Group 17, very reactive nonmetals that form salts when combined with many metals.
-Uses: to kill harmful microorganisms in hospitals, to purify drinking water and prevent growth of algae in swimming pools.

38. Student Misconceptions
*All metals are not magnetic
*Iron is not the only metal that has magnetic properties
*Electrical conductivity is not a property of only metals
*Carbon rod (graphite) is actually an element with properties that are intermediate between a metal and a nonmetal
*Not all elements are solids