1. Glencoe: Chapter 19-3 Page 588-596
The Periodic Table
Glencoe: Chapter 19-3 Page

2. Organizing the Elements
Late 1800’s (1871),
Dmitri Mendeleev
Russian chemist
Created 1st periodic table by placing all known elements (at that time ~ 60 elements) in order by increasing atomic mass (number of neutrons + number of protons)

3. Organizing the Elements
Discovered a pattern
 Heavier elements repeated the chemical properties of lighter elements
 Periodic properties – a repeating pattern of chemical properties

4. Early Periodic Tables
This table show gaps for unknown elements

5. Organizing the Elements
Mendeleev left blank spaces in his arrangement in order to attempt to align
elements with similar properties
Predicted chemical properties and atomic masses of elements not yet known, for which he had left blank spaces to be filled in when the elements were discovered.

6. Organizing the Elements
Mendeleev’s predictions were correct
When found, the
missing elements in
Mendeleev’s table did
possess properties and
masses very close to
Mendeleev’s predictions
Known as the “Father of the Periodic Table”

7. Improving the Periodic Table
As more elements were discovered, Mendeleev’s table needed some changes to deal with inconsistencies
1913 – Henry Moseley
(English scientist) –
arranged the elements
by increasing atomic
number (number of protons)

8. Improving the Periodic Table
This new arrangement corrected some inconsistencies in the periodic properties
The modern / current periodic table is arranged by increasing atomic number, from Moseley.

9. Periodic Table

10. Periodic Table

11. Table Parts
Groups – vertical columns (up-and-down) of elements on the periodic table
All elements in a group share / possess similar chemical properties, and electron arrangements
Also called families of elements
There are 18 groups / families of elements

12. Table Parts
Periods – horizontal rows (side-to-side) of elements on the periodic table
There are 7 periods
Elements increase atomic number from left to right across a period

13. Regions of the Table / Classifications
There are four general regions on the periodic table.
1. Metals
2. Metalloids
3. Non-metals
4. Noble gases

14. Table Regions

15. Synthetic elements / Man-made elements
Scientists are continually attempting to make new, bigger (higher atomic number), and heavier elements
They smash particles and atoms together to see what “sticks”

16. Synthetic elements / Man-made elements
Most break down on their own  radioactive
Radioactive elements / isotopes of elements are unstable and break apart on their own into parts that are more stable

17. Elements in the Universe
Through study it appears that the universe is made of all the same stuff
Hydrogen (H) and Helium (He) are the most abundant elements in the universe.

18. Elements in the Universe
Heavier elements are constantly being formed in stars by nuclear fusion (joining of smaller nuclei into larger nuclei).