1. Basic Chemistry
The Periodic Table

2. The Periodic Table
Organized by Dmitri Mendeleev 1869 to illustrate periodic trends in the known elements
In its present form, the periodic table allows us to identify properties of elements and their trends

3. The Periodic Table

4. Periods & Families
The rows or periods of the periodic table tell us how many energy levels are found in atoms of each element
The columns or families (also called groups) show us the general properties of each element – how its atoms combine with other elements, how it reacts, etc.

5. Atomic Number & Atomic Mass
The atomic number tells us how many protons are in each atom
The mass number tells us how many total protons and neutrons are found in an average atom
Some atoms have more or fewer neutrons than average – this is why the number is expressed as a decimal 23 V
Vanadium
50.942

6. Energy Levels
The number of electrons in a neutral atom equals the number of protons
Electrons are arranged in different energy levels
Each energy level can hold a maximum number of electrons
The outermost one can never hold more than 8

7. Families and Valences
The number of electrons in the outermost energy level tells us how atoms can combine with other atoms to make compounds
All atoms “want” to have a complete outer level and will lose, gain, or share electrons to accomplish this
The number of electrons an atom usually gains or loses is called its valence number

8. Valence Numbers
You can figure out an element’s valence number by looking at which column or family it is found in +1 +2 +3 4 -3 -2 -1
Varies

9. Other Periodic Table Information
Notice the zigzag line on the table – elements to the left are metals; those to the right are nonmetals; those on the line are metalloids
Nonmetals
Metalloids
Metals

10. Compounds
When atoms of different elements join together, they form compounds
Generally, compounds formed from a metal and a nonmetal are called ionic compounds
Those formed from two or more nonmetals are called covalent compounds
We will discuss these compounds and how they are formed in the next part of this unit