One way to organize a large group of objects is to arrange them into groups of similar objects. This is how scientists organize all of the many elements. Practice the skill of categorizing using the list of magazines below.

Calling All Girls Homeopathic Medicine Modern HousekeepingComputer World Sports and Scores Easy Car RepairsBeautiful Homes Calling All Boys The Health NewsletterAuto Racing All About Computing Football StoriesThe Healthy Man Home Decorating Read Aloud StoriesSporting Times Classic Cars Building a Web SiteChild’s Play The Healthy Woman Home Makers MagazineFamily Computing Golf for Everyone The Sports Car StoryModern Homes Nursery Rhymes Good NutritionCar Trends How to Use the Internet Tennis Tips

Bellringer/Section 2 Notes. Notebook #5 (2-9-11)

1. Arrange the magazines into similar groups.2. What criteria did you use for grouping the magazines?3. Once you arrange the magazines into groups, could you sort the

material further to make it even more organized?

I. Organization of the Periodic TableA. Periodic Law – Elements are arranged based on their

characteristics

1. This ensures the properties of elements follow a regular pattern

B. Each vertical column is called a group OR family

1. Elements in a group have similar properties.

2. They have similar properties because they have the same # of electrons in their outer energy level

3. We can represent the valence electrons by making an electron dot diagram – uses the symbol of the element & dots to represent the electrons in the outer energy level

Ar

F

Argon

Fluorine

C. Periods – Horizontal rows. Number of energy levels

II. Ions

A. A charged atom is called an Ion

2. Ions may have a positive charge or a negative charge

a. Positively charged ion – cation

b. Negatively charged ion – anion

1. Ions are formed when atoms gain or lose electrons

III. How Do The Structures Of Atoms Differ?

A. Atomic Number – The number of protons in an atom

1. Since atoms are neutral, the atomic number also gives the number of electrons

B. Mass Number – The number of protons PLUS the number of neutrons

C. Isotopes – Atoms that have a different number of neutrons

Practice/Review

Draw Electron-dot diagrams for the following elements:

1. Boron

2. Sodium

3. Lithium

4. Phosphorus

5. Helium

Example:Carbon

Mass Number:

Atomic Number:

Symbol:

Period:

Group:

# of Neutrons:

# of Electrons:

# of Protons:

# of energy levels:

# of valence electrons:

6

12.01

2

14

6

6

6

C

2

4

X

Model:- Protons- Neutrons

- Electrons XXX

X

XX