PRASEODYMIUM

Atomic symbol: Pr

Atomic weight: 140.90765

Atomic number: 59

Electron configuration: 2-8-18-21-8-2

Oxidation states: +3

State of matter: solid

Heavy metal, brittle

Discovered in 1885 by Carl Auer von Welsbach

Boils at 3212°C, melts at 931°C

Notes:
Praseodymium is a silver, moderately soft, ductile, and malleable metal. Small amounts of praseodymium are used in a rare-earth alloy used to make cigarette lighter flints and high strength low-creep magnesium alloys used for jet-engine parts.

RADIUM

Atomic symbol: Ra Atomic weight: (226.0254)

Atomic number: 91

Electron configuration: 2-8-18-32-18-8-2

Oxidation states: +4, +5

State of matter: solid

Light metal

Discovered in 1898 by Pierre and Merie Curie and assistant G. Bémont

Boils at approx. 1737°C, melts at 700°C

Notes:
Radium is a brilliant white metal that blackens when exposed to air. It is used in cancer therapy and luminescent paint.  Concentrated radium glows in the dark and gives off heat.

RADON

Atomic symbol: Rn Atomic weight: (222.0176)

Atomic number: 86

Electron configuration: 2-8-18-32-18-8

Oxidation states: +0

State of matter: gas

Noble gas

Discovered in 1900 by R.B. Owens and E Rutherford

Boils at -62°C, melts at -71°C

Notes:
Radon is a colorless, odorless, tasteless, inert, monatomic gas. It is a radioactive element that gives off a soft yellow to orange red light when in a solid state. It is often used to initiate chemical reactions.

RHENIUM

Atomic symbol: Re Atomic weight: 186.207

Atomic number: 75

Electron configuration: 2-8-18-32-13-12

Oxidation states: +4, +6, +7

State of matter: solid

Heavy metal- ductile

Discovered in 1925 by Ida & Walter Noddack and Otto Carl Berg

Boils at 5627°C, melts at 3180°C

Notes:
Rhenium is a black to silver-gray metal. It is one of the densest elements. The metal and its alloys are used in fountain pen points, high temperature thermocouples, catalysts, electrical contact points, instrument bearing points, and in electrical components.

RHODIUM

Atomic symbol: Rh Atomic weight: 102.90550

Atomic number: 45

Electron configuration: 2-8-18-16-1

Oxidation states: 3

State of matter: solid

Heavy metal, ductile

Discovered in 1803 by William Hyde Wollaston

Boils at 3272°C, melts at 1966°C

Notes:
Rhodium is a silvery white, soft, ductile, malleable metal. Its primary use is as an alloying agent for hardening platinum. It is not corroded or tarnished in the atmosphere at room temperature, and it is highly resisted to attack by acids.

RUBIDIUM

Atomic symbol: Rb Atomic weight: 85.4678

Atomic number: 37

Electron configuration: 2-8-18-8-1

Oxidation states: +1

State of matter: solid

Light metal

Discovered in 1861 by Robert Bunsen and Gustav Kirchoff

Boils at 688°C, melts at 38.9°C

Notes:
Rubidium is the second most reactive metal—it is lustrous and silver-white in color. It rapidly tarnishes when exposed to air. Rubidium can spontaneously ignite in the presence of air and reacts violently with water.

RUTHENIUM

Atomic symbol: Ru Atomic weight: 101.7

Atomic number: 44

Electron configuration: 2-8-18-15-1

Oxidation states: +3

State of matter: solid

Heavy metal, ductile

Discovered in 1844 by Karl Karlovich Klaus

Boils at 3900°C, melts at 2250°C

Notes:
Ruthenium is a lustrous silver-gray, hard metal that does not react with acids and is not oxidized by air in the cold. It looks similar to platinum but is harder, more brittle, and much more rare. Upon heating it combines readily with oxygen. It is useful in hardening platinum and palladium as an alloy. Ruthenium is found among the fission outputs of uranium and plutonium in nuclear reactors. Ruthenium has four allotropic forms. The metal doesn’t tarnish in air at normal temperatures and resists attack by many strong acids.

SCANDIUM

Atomic symbol: Sc Atomic weight: 44.955910

Atomic number: 21

Electron configuration: 2-8-9-2

Oxidation states: +3

State of matter: solid

Heavy metal, brittle

Discovered in 1879 by Lars Fredrick Nilson

Boils at 2832°C, melts at 1539°C

Notes:
Scandium is a rare earth metal widely dispersed in nature. It has very few uses, and its low density and high melting point suggest applications as an alloying agent for devices requiring lightweight metals. Scandium emits strong gamma radiation with an 85-day half-life. The chemistry of this element is similar to aluminum and titanium.

SELENIUM

Atomic symbol: Se

Atomic weight: 78.96

Atomic number: 34

Electron configuration: 2-8-18-6

Oxidation states: +4, +6, -2

State of matter: solid

Non-metal

Discovered in 1818 by Jöns Jacob Berzelius

Boils at 685°C, melts at 50 or 217°C

Notes:
Selenium exists in many allotropic forms— amorphous, crystalline or red, and gray or metallic. It occurs in both amorphous and gray states, which is why it has two melting points. It is very similar in both chemical and physical properties to sulfur and tellurium. It can convert light directly into electricity and thus makes a good element for solar cells. Selenium can also convert AC power to DC, and therefore makes a good rectifier.

SILICON

Atomic symbol: Si Atomic weight: 28.0855

Atomic number: 14

Electron configuration: 2-8-14

Oxidation states: +2, ±4

State of matter: solid

Non-metal

Discovered in 1818 by Jöns Jacob Berzelius

Boils at 2355°C, melts at 1415°C

Notes:
Silicon is black-gray and a poor conductor of electricity. It is never found free always combined with oxygen. The two principal combinations of silicon are silicon dioxide, which is found as flint, quartz, sand, sandstone, agate and amethyst and silicate rocks. These rocks range from garnet to asbestos.

SILVER

Atomic symbol: Ag Atomic weight: 107.8682

Atomic number: 47

Electron configuration: 2-8-18-18-1

Oxidation states: 1

State of matter: solid

Heavy metal, ductile

Discovered in ancient times

Boils at 2212°C, melts at 960.8°C

Notes:
Silver is a white, precious metal, more malleable and ductile than any other metal except for gold. It is the best conductor of heat and electricity. It is very rare, and the largest percentage of silver is found in lead sulfide. Silver bearing ores are called argentiferous. The biggest demand for silver comes from photography because silver is used in film.

SODIUM

Atomic symbol: Na Atomic weight: 22.989768

Atomic number: 11

Electron configuration: 2-8-1

Oxidation states: +1

State of matter: solid

Light metal

Discovered in 1807 by Sir Humphry Davy

Boils at 883°C, melts at 97.8°C

Notes:
Sodium is a light silvery-white metal, lustrous when freshly cut, but tarnishes when exposed to air, becoming dull and gray. It is too active to be found in nature, and reacts vigorously with water, exploding upon contact with a large chunk. Most metallic sodium is used in the manufacture of tetraethyl lead, an alternative for gas. Other uses are the manufacture of a variety of organic chemicals, and the reduction of titanium metal. It is also a good electron source for photoelectric cells and cyclotrons.

STRONTIUM

Atomic symbol: Sr Atomic weight: 87.62

Atomic number: 38

Electron configuration: 2-8-18-8-2

Oxidation states: +2

State of matter: solid

Light metal

Discovered in 1808 by Sir Humphrey Davy

Boils at 1384°C, melts at 769°C

Notes:
Strontium is a silvery white metal that rapidly becomes yellow when exposed to air. To prevent this oxidation it is stored in kerosene. It is ductile and malleable and can easily conduct current. The heat radioactive strontium emits due to radioactive decay can be used to generate small amounts of electricity. When finely divided, it spontaneously ignites in the presence of air.

SULFUR

Atomic symbol: S

Atomic weight: 32.066

Atomic number: 16

Electron configuration: 2-8-6

Oxidation states: +4, +6, -2

State of matter: solid

Non-metal

Discovered in ancient times

Boils at 444.7°C, melts at 112.8°C

Notes:
Because sulfur is the least reactive non-metal at room temperature, much occurs free in nature. Chemically combined, sulfur is found as sulfide ores, sulfate ores, in petroleum, and in organic matter. Sulfur has three allotropic forms, rhombic sulfur- stable at room temperature, monoclinic sulfur- which is stable between 95.6°C and its melting point, and amorphous sulfur- a plastic rubbery form. All forms slowly revert back to the rhombic form if allowed to stand at room temperature. Its uses are the making of sulfur dioxide, sulfuric acid, matches, black gunpowder, insecticides, and sulfa drugs. Much is used in vulcanizing rubber.