The Periodic Table

Chemistry Joke Two atoms walking down the street run into each other. One says to the other, "Are you all right?" "No, I lost an electron!" "Are you sure?" "Yeah, I'm positive!"

Chemcatalyst What do you notice about the numbers when you go across the periodic table and when you go down? There are several blanks on the periodic table, what do you think these represent?

Dimitri Mendeleev

Dimitri Mendeleev’s Table He grouped the elements in columns by similar properties and in order of increasing atomic mass. He predicted the properties of several elements before they were discovered.

The Modern Periodic Table Elements are still grouped by similar properties in the same column or group. But… Now they are ordered by increasing atomic number instead of increasing atomic mass. Thanks to Henry Moseley, who determined the atomic numbers!

Horizontal rows are called PERIODS. There are 7 periods 1 2 3 4 5 6 7

Vertical columns are called groups or families Vertical columns are called groups or families. Elements in groups (or columns) exhibit similar properties. 18 1 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12

Representative Elements Exhibit a wide range of both physical and chemical properties Groups 1A through 8A (or groups 1-2, and 13-18)

The elements in the colored groups are representative elements. 3B 4B 5B 6B 7B 8B 9B 10B 11B 12B

Metals Conductors of heat and electricity Have luster Malleable and ductile

Nonmetals Brittle as solids Can also be gases or liquids Non-conductors Non-lustrous

Semi-metals or Metalloids Properties of both metals and nonmetals Because they can have their conductivity manipulated, they are referred to as semiconductors and are used in microprocessors, LEDs, and solar cells. B Al Si Ge As Sb Te Po At Bold Staircase separates metals on the left from nonmetals on the right.

Alkali Metals Alkaline Earth Metals

Inner Transition Metals Groups 3 – 12, or the “B” Group Inner Transition Metals

Noble Gases Halogens

Color Coding of Periodic Table Each element on our periodic table is color coded according to the physical state of the element when it’s in its natural state. Red indicates a gas. Blue indicates a liquid. Black indicates a solid. White (outlined) indicates elements that don’t occur naturally.

Chemistry Joke Q: What is the name of the molecule CH2O? A: Seawater!