Lewis Dot Structures

Notes for page 37.

Bohr Diagrams show ALL electrons.

Lewis Dot Structures show only the electrons in the last orbital of the Bohr Diagram.
These electrons are called Valence Electrons.

Valence Electrons

• Electrons in the outermost orbital of an atom
• The reactive electrons
• Determine an element's physical and chemical properties
• Found by looking at Group # on the PT (excluding Transition Metals)

Lewis Dot Structures are used to

• Show # of valence electrons
• Show bonding between atoms

How to draw a Lewis Dot Structure:
1) Find the element on the PT
2) Write down the element's symbol
3) Find the element's Group #
4) Draw Valence Electrons around the symbol (starting at the top, moving clockwise, one at a time until all sides are filled, then pair)
How Group # corresponds to Valence Electron #

The Periodic Table of Elements

Notes for Page 13

Chemistry hinges on The Periodic Table.

This is the Periodic Table that will be given to you when you take TAKS. (click to view a larger picture)

You can find multiple things on this Periodic Table (PT from here on out).

1) At the top is a picture of the element Silicon. In this picture, TAKS shows you where the Atomic Number, Atomic Mass, Symbol, and Name can be found.

Atomic Number = # of protons
Atomic Mass = average atomic mass of the element, # protons + # neutrons

2) Across the top of the PT are Roman Numerals IA-VIIIA. These are called Groups and will help you find valence electron number and oxidation number.

3) Down the PT are numbers 1-7. These are referred to as Periods and tell you how many orbitals an element has.

4) There is a bold line that looks like a "staircase." Along this line are the elements Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, and Polonium. These are Metalloids.

5) To the left of the metalloids are metals. To the right of the metalloids are non-metals.

6) The elements in Group 1 are the Alkali Metals.

7) The elements in Group 2 are the Alkaline Earth Metals.

8) The elements in Groups 3-12 are the Transition Metals.

9) The elements in Group 17 are the Halogens.

10) The elements in Group 18 are the Noble Gases.

Websites

This is a great website that shows the PT according to names of groups and allows you to click on individual elements.