1. Periodic Table of Elements

2. Dimitri Mendeleev Russian scientist 1869 noticed that he arranged elements by their atomic mass
Present day periodic table arranged by atomic #

3. Period – Horizontal row on the Periodic Table Group/Family – Vertical column on the Periodic Table

4. Groups…Here’s Where the Periodic Table Gets Useful!!
Elements in the same group have similar chemical and physical properties!!
(Mendeleev did that on purpose.)
Why?
They have the same number of valence electrons.
They will form the same kinds of ions.

5. Groups are also called families. They are vertical columns.

6. Periods Row on the period table
Elements in the same period have the same number of electron rings
Very different properties as you move across the table
Examples:
Period 1~ H and He 1 electron shell
Period 2~ Li, Be, B, C, N, O, F, 2 electron shells
Etc……..

7. Periods are horizontal rows.

8. Periodic means having regular patterns or cycles that occur.
Chemical symbols- first letter is always capitalized and the second letter is lower case.
Elements names are often in different languages. Ex. Sodium (Na) latin word natrium

9. 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).
Soft enough to cut with a butter knife
1 valence electron

10. Alkaline Earth Metals Second column on the periodic table. (Group 2)
Reactive metals
Always combined with nonmetals in nature.
Several are important mineral nutrients (Mg and Ca)
2 valence electrons

11. Transition Metals Elements in groups 3-12 Less reactive harder metals
Includes metals used in jewelry and construction.
Metals used “as metal.”

12. Halogens Elements in group 17
Very reactive, volatile, diatomic, nonmetals
Always found combined with other element in nature
Used as disinfectants and to strengthen teeth

13. The Noble Gases

14. The Noble Gases Elements in group 18
VERY unreactive (STABLE), monatomic gases
Used in lighted “neon” signs
Have a full valence shell.

15. Ions
When atom loses or gains an electron becomes either positive or negative ion
An ion is an atom that has an electrical charge because it no longer has an equal number of protons and electrons.

16. Gaining an electron an atom becomes a negative ion (increasing # of negative charges)
losing an electron decreases its # of negative charges and becomes a positive ion.

17. Ions cont.
Need to lose or gain 1,2,or 3 electrons to have the energy levels full

18. Word Bank Periods Groups Metals Metalloids Non-metals Atomic # Mass #
Valence electrons
Electrons
Protons
neutrons
Electrons
Negative ions
Positive ions
Similar
Dissimilar
Energy levels

20. Open text book to Page 74
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