The Periodic Table of Elements

1. History of the Periodic Table

A. Early Civilizations knew of elements, such as iron, gold and silver.

B. 1669: 1st scientific discovery of an element: phosphorus

C. 1700: 12 elements were known and named.

D. 1830: 55 different elements had been isolated and named.

2. Dimitri Mendeleev

A. Russian Chemist.B. Father of the modern periodic

table.C. 1869: published the 1st periodic

table based on properties and mass.

D. Pattern showed that elements with similar properties fell into the same groups.

E. 30 years before 1st sub-atomic particles were discovered.

2. Dimitri MendeleevF. Even left space for elements he knew should exist

(due to patterns he found) but not yet discovered.G. Within 15 years, 3 elements he predicted (gallium,

scandium, germanium), were found.

H. Remember: The #s are mass, not protons.

I. Notice the ? @ 45, 68, 70

J. Look at the columns as if they were rows – what do they resemble?*Europeans use

commas as decimals

3. Henry MoseleyA. Worked under

Rutherford.B. 1914: Redesigned

Mendeleev’s table according to atomic number.

C. This redesign solved the discrepancies of Mendeleev’s table.

D. Left many spaces for missing (undiscovered) elements.

•Killed in action during World War I.

4. Periodic Table: Types of ElementsA. Metals: elements that have luster, are malleable and ductile,

and are good conductors of heat & electricity. (left, in blue)B. Nonmetals: elements that are usually brittle solids or gases

at room temperature and poor conductors. (right, in yellow)C. Metalloids: elements that share some properties with metals

and some with nonmetals. (stair-step, under gases, in green)

D. Representative elements: columns 1 & 2, 13 – 18

E. Transition elements: columns 3 – 12

F. Inner Transition elements: below the main table

5. Alkali Metals: Group 1 (1a)A. Silvery solid; soft compared to other metalsB. Low density and low melting pointC. Extremely reactive; especially in waterD. 1 valence electron

1. Very easy to lose 1 electron E. Reactivity INCREASES as you go down the family.1. Francium is much

more reactive than Lithium.

F. Hydrogen is not a metal but is grouped here because of its number of valence electrons.

6. Alkaline Earth Metals: Group 2 (2a)A. Denser, harder, higher melting point than group 1B. Conducts electricity wellC. Very reactive but not as much as group 1D. 2 valence electrons

1. Easy to lose 2 electrons

E. Reactivity INCREASES as you go down the family.

1. Radium is much more reactive than Beryllium.

7. Boron Family: Group 13 (3a)A. Metals except for Boron, which is a metalloidB. These elements are used in a variety of productsC. Reactive; Bonds with other elements by sharing

electrons.D. 3 valence electrons

1. Needs to lose 3 electrons

E. Reactivity INCREASES as you go down the family.

1. Thallium is more reactive than Boron.

8. Carbon Family: Group 14 (4a)A. Metals, nonmetals, and metalloidsB. Bond with many elements by sharing electronsC. Silicon is a semiconductor:

1. Extremely abundant metalloid2. Used in computer chip manufacturing – “Silicon Valley”

D. 4 valence electrons1. Lose 4 or gain

4; same difference

9. Nitrogen Family: Group 15 (5a)A. Metals, Nonmetals, and

MetalloidsB. Reactive: Bonds with other

elements by sharing electrons

C. Useful to living things in small amounts; deadly in large amounts

D. 5 valence electrons1. Needs to gain 3 electrons

E. Reactivity DECREASES as you go down the family.

1. Nitrogen is more reactive than Bismuth.

10. Oxygen Family: Group 16 (6a)A. Nonmetals and MetalloidsB. Oxygen & Sulfur are essential for life; Selenium

conducts electricity when exposed to lightC. Very reactiveD. 6 valence electrons

1. Easy to gain 2 electrons

E. Reactivity DECREASES as you go down the family.

F. Oxygen is more reactive than Polonium.

11. Halogens: Group 17 (7a)A. Nonmetals, except Astatine (radioactive metalloid)B. Halogen means “salt-former”C. Highly reactiveD. 7 valence electrons

1. Very easy to gain 1 electron to fill shell

E. Reactivity DECREASES as you go down the family.

1. Fluorine is extremely reactive, whereas Iodine is the least reactive.

12. Noble Gases: Group 18 (8a)A. NonmetalsB. Inert; they do not react with other elementsC. Used in various types of lightingD. 8 valence electrons (orbital is full)

E. Helium is less dense than air and is used in all types of balloons.

F. Helium is safer than hydrogen, because Hydrogen catches fire.

13. Transition Elements: Groups 3 – 12

A. All are metals; shiny, hard, lustrousB. Most are found combined with other elements in oresC. Most have higher melting pts than Representative ED. Mercury is the only liquid at room temperature

Transition Elements (in yellow)

E. Special groups: (‘group’ does not refer to a column.)

1. Iron Triad: Iron, Cobalt, Nickel

2. Platinum Group: Ruthenium, Rhodium, Palladium, Osmium, Iridium, Platinum

14. Inner Transition Elements

A. Found below the main table.

B. Lanthanides: naturally occurring except Promethium1. Soft metals; can be cut w/a knife

2. Very similar; hard to separate when together as an ore

C. Actinides: synthetic (except Thorium, Protactinium, Uranium)1. Radioactive

2. Unstable nuclei; decay to form other elements