1. The Periodic Table

2. The Periodic Table
Dmitri Mendeleev ( ) determined the properties of every known element at the time
Atomic Mass
Density
Colour
Melting Point
Boiling Point

3. The Periodic Table: Periods
Mendeleev arranged the known elements in order of increasing atomic mass
He found that the properties of the elements repeated at definite, or PERIODIC, intervals
Na has similar properties to Li and K

4. The Modern Periodic Table: Atomic Number
In 1915, the Periodic Table was reorganized based on the element’s atomic structure
Each element has an ATOMIC NUMBER, which is unique to each element
The atomic number begins with H (1) in the upper-left hand corner, and increases as you move from left to right

5. The Modern Periodic Table: Groups of Elements1 18 2

6. The Modern Periodic Table: Groups
Vertical columns in the
periodic table
Chemical families
Elements in a group share very similar properties
Numbered from 1-18
Elements in the same GROUP have the same number of VALENCE ELECTRONS (electrons in the valence or outermost shell)

7. Group 1: Alkali Metals
Very reactive metals that do not occur freely in nature (Cs, Fr the most reactive)
Valence Electrons: One; ready to lose that one electron to bond with other elements.
Properties: Malleable, ductile, good conductors of heat and electricity, softer than most metals
Can explode if exposed to water.
alkali metals in water

8. Group 2: Alkaline Earth Metals
Very reactive
Valence Electrons: 2; can bond easily with other elements by losing these electrons
Not found free in nature

9. Groups 3-12: Transition Metals
Properties: Ductile, malleable, conduct electricity and heat
Valence Electrons: transfer electrons to nonmetals to form compounds; the number of electrons transferred can vary
Iron, cobalt, and nickel are the only elements known to produce a magnetic field.

10. Group 17: Halogens
“Salt-former” because they are very reactive non-metals; form salts when they react with metals
Valence Electrons: 7; will bond easily with Alkali Metals.
Exist as solids (I, At), liquid (Br), and gas (F, Cl)
reactivity of halogens

11. Group 18: Noble Gases
Valence Electrons: full valence shell; prevents gases from forming compounds
Very stable because they have the maximum electrons in their outer shell

12. Rare Earth Elements
Lanthanide and Actinide series (Group 3 and Period 6-7)
One element of the lanthanide series and most of the elements in the actinide series are trans-uranium (synthetic or man-made)

13. Mendeleev’s Periodic Law
If the elements are arranged according to their atomic mass, a pattern can be seen in which similar properties occur regularly