1. The Periodic Table

2. Why is the Periodic Table important to me?
Its a useful tool
You can use it on your tests.
It organizes lots of data about elements.
It lets you predict what type of bonds will form
It lets you predict what type of ion will form

3. Dmitri Mendeleev

4. Dimitri Mendeleev (1869) Chemistry Professor
Wrote the first Chemistry Book
While organizing elements into chapters…
Saw patterns in their chemical properties that matched their physical properties
Used these paterns to create the Periodic Table of elements (56 of them at the time)

5. Mendeleev’s Periodic Law
"the physical and chemical properties of the elements are periodic function of their atomic masses".
Periodic = repeating
Saw repeating patterns if elements were lined up by atomic mass

6. Mendeleev’s Table He put the elements in order of atomic mass
When the patterns began to repeat he started a new row.
Elements in each column had similar properties.
He had to leave some blanks…said that undiscovered elements went there

7. SOME PROBLEMS…
He broke the pattern of increasing atomic weight to keep similar reacting elements together.
Not all elements seemed to fit his pattern

8. The Current Periodic Table
Mendeleev wasn’t too far off.
Now the elements are put in rows by increasing
ATOMIC NUMBER!!
The horizontal rows are called periods and are labeled from 1 to 7.
The vertical columns are called groups are labeled from 1 to 18.

9. General Areas & Their Properties
Metals
Nonmetals
Metalloids

10. Metals Shiny Malleable Ductile good conductors
high melting points and boiling points
usually solids

11. Nonmetals Not shiny Nonmalleable Not ductile Poor conductors
Low melting and boiling points

12. Metalloids
Elements that are not metals or nonmetals but have a mixture of both properties

13. Groups…Here’s Where the Periodic Table Gets Useful!!
Elements in the same group have similar chemical and physical properties!!
Why??
They have the same number of valence electrons.
They will form the same kinds of ions.

14. Families on the Periodic Table
Columns are also grouped into families.
Families may be one column, or several columns put together.
Families have names rather than numbers. (Just like your family has a common last name.)

15. Families

16. Hydrogen Hydrogen is its own family it is a diatomic, reactive gas
Reacts quickly because it only needs to lose 1 electron to have a full outer shell
Hydrogen caused the Hindenberg to explode
Hydrogen is promising as an alternative fuel source for automobiles

17. Alkali Metals 1st column on the periodic table
(Group 1) not including hydrogen.
Very reactive metals, always combined with something else in nature (like in salt).
React quickly bcs only need to lose 1 e-
Soft enough to cut
with a butter knife

18. Alkaline Earth Metals Second column on the periodic table. (Group 2)
Reactive metals that are always combined with nonmetals in nature
(react quickly - only need to lose 2 e-)
important mineral nutrients
Mg and Ca

19. Transition Metals Elements in groups 3-12 Less reactive harder metals
used in jewelry and construction
Metals used “as metal.”
Have more than one oxidation #
Lanthanide and Actinide Series are very radioactive!

20. Halogens Elements in group 17
Very reactive nonmetals (need to gain 1e-)
Attract electrons VERY strongly
Always combined with other element in nature.
Diatomic =
atoms come in pairs never alone
Used as disinfectants
and to strengthen teeth.
Teflon = F bonded to C

21. The Noble Gases Elements in group 18 VERY un-reactive (inert)
Used in lighted “neon” signs
Used in blimps to fix the
Hindenberg problem.
Have a full outer electron shell
so don’t need to react to get full outer shell

22. Ionization Energy vs Electronegativity
How hard the protons in the nucleus pull on electrons
Decreases as you get farther from the nucleus
Coulombs Law says…
Force of attraction =
Charge e- * charge P
distance2
How much energy it takes to remove outermost electron
Further away from nucleus makes less force of attraction so
Lower ionization energy

23. Atomic Radius
Distance from the center of the nucleus to the outermost edge of the electron cloud

24. Periodic Trends
This trend also tends to repeat as you go from one row to the next
This is called periodicity, meaning the trend occurs in cycles
Each horizontal row is called a period because it corresponds to one full cycle of a trend
There are many properties that change gradually in moving from left to right across the table

25. Periodic Trends
Radius decreases from left to right, increases as you move down a group

26. Atomic Size - Group trendsH
As we increase the atomic number (or go down a group). . .
each atom has another energy level,
so the atoms get bigger. Li Na K Rb

27. Atomic Size - Period Trends
Going from left to right across a period, the size gets smaller.
Electrons are in the same energy level.
But, there is more nuclear charge.
Outermost electrons are pulled closer. P S Cl Ar Si Na Mg Al

28. Trends in Electronegativity
Electronegativity is the tendency for an atom to attract electrons to itself when it is chemically combined with another element.
They share the electron, but how equally do they share it?
An element with a big electronegativity means it pulls the electron towards itself strongly!

29. Electronegativity Group Trend
The further down a group, the farther the electron is away from the nucleus, plus the more electrons an atom has.
Thus, more willing to share.
Low electronegativity.

30. The arrows indicate the trend: Ionization energy and Electronegativity INCREASE in these directions

31. Electronegativity Period Trend
Metals are at the left of the table.
They let their electrons go easily
Thus, low electronegativity
At the right end are the nonmetals.
They want more electrons.
Try to take them away from others
High electronegativity.