Element Information
Atomic Numbers 11 through 20

red block.gif (2946 bytes)
spinning blue box.gif (4275 bytes) Back to elements 1-10        spinning blue box.gif (4275 bytes) Return to periodic table       spinning blue box.gif (4275 bytes) Go to elements 21-30

    This page contains basic information about elements with atomic numbers 11 through 20.  I have tried to make sure the information is correct, but if you find a mistake, please e-mail me at apurdy@centurytel.net, and I will correct it as soon as possible.

Sodium                             multicolored.gif (1741 bytes)  Click here to return to periodic table  

Symbol Na Name Sodium
Atomic Number 11 Atomic Mass 22.98977 amu
Melting Point 97.81C Boiling Point 892C
Protons/Electrons 11 Neutrons 12
Classification Alkali Metal State Solid
Density 0.971 g/cm3 Period/Group 3 / 1
Electronegativity 0.93 Atomic Radius 186 pm
# of Isotopes 1 Color silvery
Energy Levels 3 Crystal Sturcture cubic
Sir Humphrey Davy discovered sodium in its elemental form in 1807.  The symbol Na is derived form its Latin name natrium.                                        

Uses - lamps, table salt, medicine, agriculture

 

Magnesium                       multicolored.gif (1741 bytes)  Click here to return to periodic table  

Symbol Mg Name Magnesium
Atomic Number 12 Atomic Mass 24.312 amu
Melting Point 651C Boiling Point 1107C
Protons/Electrons 12 Neutrons 12
Classification Alkaline Earth Metal State Solid
Density 1.74 g/cm3 Period/Group 3 / 2
Electronegativity 1.31 Atomic Radius 160 pm
# of Isotopes 3 Color silvery
Energy Levels 3 Crystal Sturcture hexagonal
Sir Humphrey Davy was the first to isolate magnesium in 1808.                   

Uses - alloys, flashbulbs, airplanes, missles, flares, fireworks, medicine

 

Aluminum                      multicolored.gif (1741 bytes)  Click here to return to periodic table  

Symbol Al Name Aluminum
Atomic Number 13 Atomic Mass 26.9815 amu
Melting Point 660C Boiling Point 2467C
Protons/Electrons 13 Neutrons 14
Classification Other Metal State Solid
Density 2.70 g/cm3 Period/Group 3 / 13
Electronegativity 1.61 Atomic Radius 143 pm
# of Isotopes 1 Color silvery
Energy Levels 3 Crystal Sturcture cubic
Crude aluminum was isolated in 1825 by Hans Christian Orsted.   Friedrich Wohler produced aluminum powder in 1827 and small globules of the metal in 1845.  The new metal was introduced to the public in 1855 at the Paris exposition.                                               

Uses - aluminum cans and foil, reflectors, airplanes, kitchen utensils, building material

 

Silicon                               multicolored.gif (1741 bytes)  Click here to return to periodic table 

Symbol Si Name Silicon
Atomic Number 14 Atomic Mass 28.086 amu
Melting Point 1410C Boiling Point 2355C
Protons/Electrons 14 Neutrons 14
Classification Metalloid State Solid
Density 2.42 g/cm3 Period/Group 3 / 14
Electronegativity 1.9 Atomic Radius 117.6 pm
# of Isotopes 3 Color gray-black
Energy Levels 3 Crystal Sturcture diamond
Silicon was first isolated and identified as an element in 1824 by Jns Jacob Berzelius, a Swedish chemist.                

Uses - computer chips, lubricant, glass, semiconductors, concrete, bricks

 

Phosphorus                         multicolored.gif (1741 bytes)  Click here to return to periodic table

Symbol P Name Phosphorus
Atomic Number 15 Atomic Mass 30.9738 amu
Melting Point 44.1C Boiling Point 280C
Protons/Electrons 15 Neutrons 16
Classification Non-metal State Solid
Density 1.82 g/cm3 Period/Group 3 / 15
Electronegativity 2.19 Atomic Radius 110 pm
# of Isotopes 1 Color yellow-white
Energy Levels 3 Crystal Sturcture triclinic
Phosphorus was first prepared in elemental form in 1669 by a German alchemist, Hennig Brand, from a residue of evaporated urine.                   

Uses - fertilizer, detergents, matches, fireworks, pesticides

 

Sulfur                                multicolored.gif (1741 bytes)  Click here to return to periodic table

Symbol S Name Sulfur
Atomic Number 16 Atomic Mass 32.064 amu
Melting Point 112.8C Boiling Point 444.6C
Protons/Electrons 16 Neutrons 16
Classification Non-metal State Solid
Density 2.07 g/cm3 Period/Group 3 / 16
Electronegativity 2.58 Atomic Radius 103 pm
# of Isotopes 4 Color pale yellow
Energy Levels 3 Crystal Sturcture orthorhombic
Sulfur was known by the ancients, and was referred to in Genesis as brimstone.  It was first classified as an element in 1777 by Antoine Lavoisier, a French chemist.                                      

Uses - rubber, batteries, matches, gunpowder, medicines, paper products

 

Chlorine                            multicolored.gif (1741 bytes)  Click here to return to periodic table

Symbol Cl Name Chlorine
Atomic Number 17 Atomic Mass 35.453 amu
Melting Point -103C Boiling Point -34C
Protons/Electrons 17 Neutrons 18
Classification Non-metal State Gas
Density 0.003214 g/cm3 Period/Group 3 / 17
Electronegativity 3.16 Atomic Radius 100 pm
# of Isotopes 2 Color greenish-yellow
Energy Levels 3 Crystal Sturcture orthrhombic
  Chlorine was first prepared from muriatic (hydrochloric) acid and manganese dioxide in 1774 by Carl Wilhelm Scheele.  It was considered a compound until Sir Humphrey Davy showed in 1810 that it could not be decomposed and that muriatic acid consists of two simple substances: hydrogen and a true element that he named chlorine.                              

Uses - bleach, PVC pipe, water purification, cleaning compounds

 

Argon                               multicolored.gif (1741 bytes)  Click here to return to periodic table

Symbol Ar Name Argon
Atomic Number 18 Atomic Mass 39.948 amu
Melting Point -189.2C Boiling Point -185.7C
Protons/Electrons 18 Neutrons 22
Classification Nobel Gas State Gas
Density 0.001784 g/cm3 Period/Group 3 / 18
Electronegativity NA Atomic Radius 98 pm
# of Isotopes 3 Color colorless
Energy Levels 3 Crystal Sturcture cubic
Argon gas was isolated in 1894 by the English scientists Lord Rayleigh (John William Strutt) and Sir William Ramsey.                                                   

Uses - lasers, light bulbs

 

Potassium                        multicolored.gif (1741 bytes)  Click here to return to periodic table 

Symbol K Name Potassium
Atomic Number 19 Atomic Mass 39.102 amu
Melting Point 63.65C Boiling Point 774C
Protons/Electrons 19 Neutrons 20
Classification Alkali Metal State Solid
Density 0.862 g/cm3 Period/Group 4 / 1
Electronegativity 0.82 Atomic Radius 227 pm
# of Isotopes 3 Color silvery-white
Energy Levels 4 Crystal Sturcture cubic
Potassium was the first metal to be isolated by electrolysis, by Sir Humphrey Cavy, when he discovered the element in 1807.                               

Uses - fertilizer, low sodium salt, glass, soap, detergents, fireworks

 

Calcium                           multicolored.gif (1741 bytes)  Click here to return to periodic table

Symbol Ca Name Calcium
Atomic Number 20 Atomic Mass 40.08 amu
Melting Point ~844C Boiling Point 1487C
Protons/Electrons 20 Neutrons 20
Classification Alkaline Earth Metal State Solid
Density 1.55 g/cm3 Period/Group 4 / 2
Electronegativity 1 Atomic Radius 197 pm
# of Isotopes 1 Color silvery-white
Energy Levels 4 Crystal Sturcture cubic
Although calcium was extensively used by the ancients as the compound lime, the metal itself was first isolated in 1808 by Sir Humphrey Davy.                 

Uses - lime, cement, reducing agent for preparation of some metals

red moving left.gif (1471 bytes)                  red moving right.gif (1472 bytes)                            Top.gif (420 bytes)                                   
Go to elements 1-10                    Go to elements 21-30