1. How are days organized?

2. Dmitri Mendeleev Russian 1860’s
The Person Who Organized the Elements
Dmitri Mendeleev Russian 1860’s

3. Mendeleev Teacher at St. Petersburg University.
Was working on a textbook for his Chemistry students.
He organized the 63 elements known at the time.

4. His Criteria
Increasing atomic mass.
Physical and Chemical Properties.

6. Mendeleev’s Predictions
He left spaces on the table for undiscovered elements.
He predicted the properties of elements that had not yet been discovered.
Very cool!

7. This is Neon. He is a stable atom. This makes him happy!
All atoms want to have a full outer shell of electrons.
This is 2 on the first shell and 8 on the next couple of shells.
This is Neon. He is a stable atom. This makes him happy!
Why is he stable?
valence electrons: the number of e in the outer shell

8. What could you suggest to help them out?
fluorine
lithium
beryllium
These atoms are all unstable as they do not have full outer shells of electrons.
What could you suggest to help them out?
sodium
chlorine
oxygen
hydrogen

9. Periodic Trends
Groups 1 to 18 look at electron arrangement for the first 20 elements
G1 G G3 to G15 G16 G17 G18

12. Mg + O = MgO
Metal gas Metal oxide
2Mg + O MgO
Heat
Mg O2-

13. THEORY: What’s the use of electron arrangements?
Atoms join by using valence electrons. Atoms in group 18 have full levels and don’t join up. They are noble gases and unreactive
Other atoms either take, give or share electrons to get a FULL outer shell which would make them stable.
Atoms with 1,2 or 3 valence electrons prefer to LOSE
Atoms with 4 valence electrons like to SHARE their electrons
Atoms with 5,6 or 7 valence electrons TAKE or share other electrons.
Atoms with 8 valence electrons don’t usually do anything, they are stable as they are!!

15. Metals Gases GROUPS PERIODS Halogens Noble Gases Transition Metals
Alkali Metals
Alkaline Earth
Metals

16. ALKALI METALS Group 1 Hydrogen is not a member, it is a non-metal
1 electron in the outer shell
Soft and silvery metals
Very reactive, esp. with water
Conduct electricity
Image:

17. ALKALINE EARTH METALS Group 2 2 electrons in the outer shell
White and malleable
Reactive, but less than Alkali metals
Conduct electricity

18. TRANSITION METALS Groups (3 to 12) in the middle
Good conductors of heat and electricity.
Some are used for jewelry.
The transition metals are able to put up to 32 electrons in their second to last shell.
Can bond with many elements in a variety of shapes.

19. Halogens Group 17 7 electrons in the outer shell All are non-metals
Very reactive are often bonded with elements from Group 1

20. Noble Gases Group 18 Exist as gases Non-metals
8 electrons in the outer shell = Full
Helium (He) has only 2 electrons in the outer shell = Full
Not reactive with other elements