1. Chapter 5
The Periodic Table

2. Organizing the Elements
Section 1
Organizing the Elements

3. Learning Targets I can explain how the periodic table was created
I can differentiate between periods and groups

4. Elements
Science has come along way since Aristotle’s theory of Air, Water, Fire, and Earth.
Scientists have identified 90 naturally occurring elements, and the rest are man made.

5. Elements
The elements, alone or in combinations, make up our bodies, our world, our sun, and in fact, the entire universe.

6. How were the elements first organized?
1869
Dmitri Mendeleev
Published the first periodic table
Arranged elements in rows by increasing atomic mass
All the elements in a column had similar chemical properties

7. Why did Mendeleev leave gaps in the periodic table?
He predicted that scientists would eventually find the elements that would fill those gaps.

8. What was the problem with Mendeleev’s periodic table?
Some elements did not fit the pattern
He had to reverse some of the elements so that they were in columns with similar elements but now they were not in increasing mass

9. Who is noted with changing the original periodic table?
Henry Moseley
Arranged by increasing atomic number
atomictheorytimeline.blogspot.com

10. What is periodic law?
The law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements

11. What can you tell me about the rows in a periodic table?
Called periods
7 periods
Determine the number of energy levels
As you move from left to right:
Elements become less metallic
Reactivity and conductivity changes

12. What can you tell me about the columns in a periodic table?
Called groups
Elements in columns have similar chemical properties
Why?
Each column has the same number of valence electrons
chem4kids.com
modelscience.com

13. Learning Target Checkpoint
Who created the first periodic table?
How was it arranged?
Who arranged the periodic table by increasing atomic number?
Differentiate between periods and groups.