1. Classifying Elements
Chapter 6 Section 2

2. Periodic Table
A periodic table is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties.
A periodic table allows you to easily compare the properties of one element to another element.

3. Squares in the Periodic Table
The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms:
Atomic number and atomic mass
Black symbol = solid; red = gas; blue = liquid
(from the Periodic Table on our classroom wall)

4. Periodic Table Groups
Each vertical column of the periodic table is called a group, or family. Groups are numbered 1-18
Elements within a group have similar chemical and physical properties.
They have similar chemical and physical properties because they have similar electron configurations.
Example: Li = [He] 2s1 , Na = [Ne] 3s1 each has one electron is the highest energy level

5. Groups
A Group or Family

6. Periodic Table Periods
Each horizontal row of the periodic table is called a period.
Within a given period, the properties of the elements vary as you move across it from element to element.
Periods are numbered 1-7

7. Periods
A Period

8. Alkali metals
The elements of group 1 of the periodic table except Hydrogen
These elements are extremely reactive, and are never found in nature as pure elements—only found in nature in compounds.

9. 1s1
1s22s1
1s22s22p63s1
1s22s22p63s23p64s1
1s22s22p63s23p64s23d104p65s1
1s22s22p63s23p64s23d104p65s24d10 5p66s1
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1 H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87
Do you notice any similarity in these configurations of the alkali metals?

10. Alkaline Earth Metals The elements of group 2 of the periodic table
These elements are also very reactive like the alkali metals, just a little bit less reactive.
The alkaline earth metals are also only found in nature as part of a compound.

11. Group 1A are the alkali metals (but NOT H)
Group 2A are the alkaline earth metals H

12. Elements in the s - blocks
Alkali metals all end in s1
Alkaline earth metals all end in s2
really should include He, but it fits better in a different spot, since He has the properties of the noble gases, and has a full outer level of electrons.

13. halogens The nonmetal elements of group 17 of the periodic table
The name halogen comes from the combination of the Greek word hals, meaning salt, and the Latin word genesis, meaning “to be born.”
Salt forming
The most common halogens are chlorine, bromine, and iodine.

14. Electron Configurations in Groups
Elements can be sorted into 4 different groupings based on their electron configurations:
Noble gases
Representative elements
Transition metals
Inner transition metals
Let’s now take a closer look at these.

15. Noble gases
The elements of group 8A or 18 of the periodic table
These nonmetals are sometimes called the inert gases because they rarely take part in a reaction.
Noble gases have an electron configuration that has the outer s and p sublevels completely full

16. 1s2
1s22s22p6
1s22s22p63s23p6
1s22s22p63s23p64s23d104p6
1s22s22p63s23p64s23d104p65s24d105p6
1s22s22p63s23p64s23d104p65s24d10 5p66s24f145d106p6 He
Do you notice any similarity in the configurations of the noble gases? 2 Ne 10 Ar 18 Kr 36 Xe 54 Rn 86

17. Group 8A are the noble gases
Group 7A is called the halogens

18. Representative elements
The elements of groups 1, 2, and 13 through 18 or 1A-7A of the periodic table
Display wide range of properties, thus a good “representative”
Some are metals, or nonmetals, or metalloids; some are solid, others are gases or liquids
Their outer s and p electron configurations are NOT filled

19. Elements in the 1A-7A groups are called the representative elements
outer s or p filling 1A 8A 2A 3A 4A 5A 6A 7A

20. Transition metals
The elements of groups 3 through 12 or the B columns of the periodic table
Electron configuration has the outer s sublevel full, and is now filling the “d” sublevel
A “transition” between the metal area and the nonmetal area
Examples are gold, copper, silver

21. The group B are called the transition elements
These are called the inner transition elements, and they belong here

22. Transition Metals - d block
Note the change in configuration.
s1 d5
s1 d10 d1 d2 d3 d5 d6 d7 d8
d10

23. Inner transition metals
Located below the main body of the periodic table
Electron configuration has the outer s sublevel full, and is now filling the “f” sublevel
Formerly called “rare-earth” elements, but this is not true because some are very abundant
Also called the lanthanide and actinide series