1. Elements and the Periodic Table
Chapter 3
Elements and the Periodic Table

2. The Periodic Table
Dmitri Mendeleev: Russian chemist who listed the elements in several vertical columns in order of increasing atomic mass

3. The Periodic Table constructed the first periodic table (1869)
-an organization of the chemical elements based on grouping the elements by similar properties
worked with about 60 elements
he left blank spaces in the table because there were no known elements with the appropriate properties

4. The Periodic Table Organized based on two characteristics:
atomic weight
Bonding power – the ratio of how an element combines with certain other elements on the periodic table

5. The Periodic Table

6. Patterns in the Periodic Table
All atoms are composed of:
Protons
Neutrons
Electrons

7. Patterns in the Periodic Table
Protons
determine the element
Same as the atomic number
Found in the nucleus
Positive charge
Mass of 1 atomic mass unit (amu)

8. Patterns in the Periodic Table
Neutrons
Neutral
Found in the nucleus
Mass of 1 amu
An atom of the same element with different numbers of neutrons is called an isotope
Example:
Carbon- 12 or Carbon- 14

9. Patterns in the Periodic Table
Electrons
Negative charge
Found outside of the nucleus
Mass is very small
Controls the chemical behavior of an element
Valence electrons- the outer electrons that determine reactivity

10. Patterns in the Periodic Table
Atomic number = number of protons=number of electrons
Mass number = number of protons + number of neutrons
Average atomic mass- on periodic table, average of all of the isotopes masses