298 | The History and Use of Our Earth’s Chemical Elements Properties

298 | The History and Use of Our Earth’s Chemical Elements Properties

Erbium is a soft, malleable metal with a silvery metallic luster that only tarnishes (oxidizes) slightly in air. It is one of the rare-earths of the yttrium subgroup of the lanthanide series. Its melting point is 1,529°C, its boiling point is 2,868°C, and its density is 9.07g/cm 3 .

Characteristics Although erbium is magnetic at very low temperatures, it is antiferromagnetic and becomes

a superconductor at temperatures near absolute zero. It is insoluble in water but soluble in acids. Its salts range from pink to red. Erbium and some of the other rare-earth elements are considered to be “impurities” in the minerals in which they are found. Small quantities of erbium can also be separated from several other rare-earths.

Abundance฀and฀Source Erbium ranks 17th in abundance among the rare-earths, and it is the 46th most abundant

element found in the Earth’s crust. It exists in only 2.5 ppm, meaning that about 2.5 pounds of erbium could be extracted from one million pounds of dirt in the Earth’s crust. Higher con- centrations are found in some areas, but in general, the oxides of erbium are rather scarce.

It is found in ores such as monazite, gadolinite, and bastnasite. It was first separated into three elements in 1843 (yttria, erbia, and terbia). Erbium is also produced as a by-product of nuclear fission of uranium.

History Carl Gustaf Mosander, a Swedish chemist, successfully separated two rare-earths from a

sample of lanthanum found in the mineral gadolinite. He then tried the same procedure with the rare-earth yttria. He was successful in separating this rare-earth into three separate rare- earths with similar names: yttia, erbia, and terbia. For the next 50 years scientists confused these three elements because of their similar names and very similar chemical and physical properties. Erbia and terbia were switched around, and for some time the two rare-earths were mixed up. The confusion was settled ostensibly in 1877 when the chemistry profession had the final say in the matter. However, they also got it wrong. What we know today as erbium was originally terbium, and terbium was erbium.

Common฀Uses Erbium has limited commercial use, but it is used as an alloy metal for vanadium to make

it easier to work and to form spring steel. The oxide of erbium is pink, which is used to color glass and to make lasers that will operate at normal room temperatures. It has limited use as control rods in nuclear fission reactors.

Examples฀of฀Compounds Erbium has a +3 oxidation state that easily combines with the halogens and oxygen. The

“X” here can be used to represent the halide ion combining with the metallic ion of erbium, as follows:

Er 3+ + 3X 1- → ErX 3 .

There is only one oxide of erbium, which is called erbium oxide or erbia (2Er 3+ +3O 2- →

Er 2 O 3 ).

299 Hazards

Guide to the Elements |

Erbium nitrate [Er(NO 3 ) 3 ] may explode when “shocked” or at high temperatures. As with other rare-earths, erbium and its compounds should be handled with care because they can

be toxic. THULIUM SYMBOL:฀Tm฀PERIOD:฀6฀SERIES฀NAME:฀Lanthanide฀ATOMIC฀NO:฀69

ATOMIC฀MASS:฀168.9342฀amu฀VALENCE:฀3฀OXIDATION฀STATE:฀+3฀NATURAL฀STATE:฀ Solid

ORIGIN฀OF฀NAME:฀Named฀for฀Thule,฀the฀Greek฀word฀for฀Scandinavia,฀the฀most฀northerly฀ habitable฀land฀in฀ancient฀mythology. ISOTOPES:฀There฀are฀a฀total฀of฀46฀isotopes฀of฀thulium.฀One฀of฀these,฀Tm-169฀is฀the฀only฀ stable฀isotope฀of฀thulium฀and฀accounts฀for฀the฀total฀atomic฀mass฀of฀the฀element.฀All฀the฀ other฀isotopes฀are฀artificially฀produced฀and฀radioactive฀and฀have฀half-lives฀ranging฀from฀a฀ few฀microseconds฀to฀two฀years.

ELECTRON฀CONFIGURATION ฀ Energy฀Levels/Shells/Electrons฀ Orbitals/Electrons

s2,฀p6

฀ 3-M฀=฀18฀

s2,฀p6,฀d10

฀ 4-N฀=฀31฀

s2,฀p6,฀d10,฀f13

฀ 5-O฀=฀8฀

s2,฀p6

฀ 6-P฀=฀2฀

s2