1. Trends in 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 moves from Left to Right

5. 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 atomic SHELLS where VALENCE ELECTRONS (outer electrons) are held

6. Elements are grouped based on specific properties:
Nonmetals
Metalloids
Metals

7. Solid at Room Temperature Shiny Lustre
Metals
Shiny Lustre
Good Conductors (Heat/Electricity)
Gas, Solid and Liquid at Room Temperature
Non-Metals
Not Lustreous
Poor Conductors
Solids at Room Temperature
Metalloids
Shiny
Dull or
Poor Heat Conductor
May Conduct Electricity

8. The Modern Periodic Table: Characteristics of Groups
The number of valence electrons in the elements is same in a group.
The atomic radii increase from top to bottom
Metallic Elements:
Metallic character and chemical reactivity increase from top to bottom
Non-Metallic Elements:
Metallic character and chemical reactivity decrease from top to bottom

9. Mg and Ca React with Hydrochloric Acid (Same Group)
Elements are ordered in the periodic table according to reactivity and atomic number:
F, Cl, I are gases F Cl I
Mg and Ca React with Hydrochloric Acid (Same Group) Mg Ca
Na and K react with Water Na K

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

11. 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.

12. Group 2: Alkaline Earth Metals
Very reactive
Valence Electrons: 2; can bond easily with other elements
Not found free in nature

13. Groups 3-12: Transition Metals
Properties: Ductile, malleable, conduct electricity and heat
Valence Electrons: present in more than one shell
Iron, cobalt, and nickel are the only elements known to produce a magnetic field.

14. Groups 13-15: Other Metals
Properties: Ductile and malleable, solid, high density, opaque
Valence Electrons: present in their outer shell.

15. Metalloids
Along the stair-step line that distinguishes metals from non-metals
Al is an exception as it is classified as an “Other Metal”
Properties: Similar to metals and non-metals
Si and Ge are semi-conductors (can carry an electrical charge under special conditions; used in calculators and computers)

16. Group 14-16: Non-Metals
Properties: Do not conduct electricity or heat very well, brittle, not malleable or ductile, no luster, do not reflect light
Exist as gases (N, O) or solids (C, S)

17. Group 17: Halogens
“Salt-former”, compounds containing halogens are called “salts”
Valence Electrons: 7; will bond easily with Alkali Metals.
Exist as solids (I, At), liquid (Br), and gas (F, Cl)

18. Group 18: Noble Gases
Valence Electrons: 0; prevents gases from readily forming compounds
Very stable because they have the maximum electrons in their outer shell

19. 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)

20. 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