300 | The History and Use of Our Earth’s Chemical Elements AbundanceandSource
300 | The History and Use of Our Earth’s Chemical Elements AbundanceandSource
Thulium is the 61st most abundant element in the Earth’s crust and is found along with other rare-earths in monazite sand, which is about 50% rare-earths by weight. Only about 0.007% of this is thulium. It is also found in bastnasite ore. It ranks 16th out of the 17 rare- earths in abundance. Thulium is usually found as an oxide along with other rare-earths. Like most rare-earths, thulium can be separated from its ore by the ion-exchange process, where its positive ion reacts with elements with negative ions like fluorine, chlorine, or oxygen to
form binary compounds (e.g., Tm 2 O 2 ). It can also be recovered as a by-product of the nuclear fission reaction in nuclear reactors.
History In 1879 Per Theodor Cleve, a Swedish chemist, discovered thulium by looking for impu-
rities in the oxides of other rare-earths. This is the same method first used by Carl Gustaf Mosander to discover lanthanum, erbium, and terbium. After Cleve processed the oxide of
erbium (Er 2 O 3 ), two new substances remained, one green, the other brown. Cleve named the brown substance “holmia,” and the green substance he named “thulia” after the Greek word Thule, which in legend represented the most northern region that was inhabited by humans. It is now known as Scandinavia.
CommonUses Thulium is relatively scarce and expensive, which limits its commercial uses. Thulium-170,
which is a radioactive isotope of thulium produced by fission in nuclear reactors, can be used as small, portable X-ray sources. It also has limited use as an alloy metal with other metals and has experimentally been used in lasers. (Note: Of all the isotopes of thulium, only thulium- 169 is stable and nonradioactive.)
ExamplesofCompounds Similar to other rare-earths, thulium has a single oxidation state of +3. A general formula
for the positive ion of thulium and the elements found in group 7 (fluorides) with a negative ion is expressed as follows:
Tm 3+ + 3X 1- → TmX 3 , where X represents one of the fluorides.
The only oxide of thulium, which sometimes is called thulia, is produced as follows: 2Tm 3+ + 3O 2- → Tm 2 O 3 .
Hazards The dust and powder of thulium are explosive and toxic if inhaled or ingested. As with all
radioactive elements, thulium can cause radiation poisoning. YTTERBIUM SYMBOL:Yb PERIOD:6 SERIESNAME:Lanthanide ATOMICNO:70
ATOMICMASS:173.04amu VALENCE:2and3 OXIDATIONSTATE:+2and+3 NAT-
URALSTATE:Solid ORIGINOFNAME:YtterbiumisnamedfortheYtterbyquarrylocatedinSweden.
Guide to the Elements |
ISOTOPES:Thereareatotalof37isotopesofytterbium.Sevenofthesearestable,and theymakeupallofthenaturalytterbiumfoundonEarth.Oneoftheseisotopes(Yb- 176)hassuchalonghalf-life(1.6×10 +17 years)thatitcontributes12.76%ofthenatural ytterbiumexistingonEarth,andthusitisconsideredstable.Alltheother30isotopesare artificiallyradioactiveandproducedbynuclearfissioninnuclearreactorswithhalf-lives rangingfromafractionofasecondto32days.
ELECTRONCONFIGURATION EnergyLevels/Shells/Electrons Orbitals/Electrons
s2,p6
3-M=18
s2,p6,d10
4-N=32
s2,p6,d10,f14
5-O=8
s2,p6
6-P=2
s2
Properties Ytterbium is a silvery, soft, malleable, and ductile metal with a lustrous metallic shine.
It is slightly reactive in air or water at room temperatures. Ytterbium is located next to last of the rare-earths in the lanthanide series. It slowly oxidizes as it reacts with oxygen in the atmosphere, forming a somewhat duller coating. Ytterbium was the first rare-earth to be discovered by Carl Gustof Mosander in 1843. More of it exists in the Earth’s crust than once was believed.
It was often confused with other rare-earths and was known by two other names, aldebara- nium and cassiopeium. Ytterbium’s melting point is 819°C, its boiling point is 1,196°C, and
its density is 6.9654g/cm 3 .
Characteristics In the past there was some confusion about the rare-earths because they are not really earths
at all, but rather binary compounds of oxides of metals. Compounding the confusion was the fact that they were always found combined with several other rare-earths.
The salts of ytterbium are paramagnetic, which exhibit weaker magnetic fields than do iron magnets.
AbundanceandSource Ytterbium is the 45th most abundant element, and it ranks 10th in abundance (2.7 ppm)
among the 17 rare-earths found in the Earth’s crust. It is found in ores along with other rare-earths that were first found in the Ytterby quarry of Sweden. These ores are xenotime, euxenite, gadolinite, and monazite. Monazite river sand is
302 | The History and Use of Our Earth’s Chemical Elements the main source of ytterbium, which is found in India and Brazil and the beaches of Florida.
Ytterbium is also found as a decay product of the fission reaction in nuclear reactors. History
In 1843 Carl Gustaf Mosander separated gadolinite into three distinct materials, to which
he gave the names yttria, erbia, and terbia. There was some confusion as to the composition of erbia. In 1878 Jean Charles Galissard de Marignac separated erbia into two rare-earths. One
he called “ytterbia,” and the other maintained the name “erbia.” Marignac is credited with the discovery of ytterbium. Some years later, in 1907, Georges Urbain (1872–1938) believed that ytterbium was not a single element, so he experimentally separated it into what he called “neoytterbium” (new ytterbium) and a new element he called “lutecium,” whose name was later changed to “lutetium.”
CommonUses There is not much commercial use for ytterbium. Radioactive ytterbium can be used for a
small portable X-ray source and as an alloy to make special types of strong steel. The oxides of ytterbium are used to make lasers and some synthetic gemstones.
ExamplesofCompounds Since ytterbium has both a +2 and +3 oxidation state, it can form two different compounds
with the halogens. See the following examples:
Ytterbium (II) chloride: Yb 2+ + 2Cl 1- → YbCl 2 . Ytterbium (III) chloride: Yb 3+ + 3Cl 1- → YbCl 3 .
Ytterbium oxide (Yb 2 O 3 ) is used to make special alloys, ceramics, and glass. It can be used for carbon arc-lamp electrodes that produce a very bright light.
Hazards Ytterbium dust and powder can explode and may be toxic if inhaled. The compound.
ytterbium arsenate is a poison. LUTETIUM
SYMBOL:Lu PERIOD:6 SERIESNAME:Lanthanide ATOMICNO:71 ATOMICMASS:174.967amu VALENCE:3 OXIDATIONSTATE:+3 NATURALSTATE:
Solid ORIGINOFNAME:Lutetium’snameisderivedfromtheancientLatinnameforParis,
France:Lutecia. ISOTOPES:Thereareatotalof59isotopesofLutetium.Onlytwoofthesearestable:Lu- 175,whichmakesup97.41%ofallthenaturalabundancefoundonEarth.Theother isalong-livedradioisotope(Lu-176)withsuchalonghalf-life(4.00×10 +10 years)that itisconsideredstable:Lu-176contributes2.59%tothenaturalabundanceoflute- tium.
Guide to the Elements |
ELECTRONCONFIGURATION EnergyLevels/Shells/Electrons Orbitals/Electrons
s2,p6
3-M=18
s2,p6,d10
4-N=32
s2,p6,d10,f14
5-O=9
s2,p6,d1
6-P=2
s2
Properties In the last (17th) position in the lanthanide series, lutetium is the heaviest and largest
molecule of all the rare-earths as well as the hardest and most corrosion-resistant. It has a silvery-white color and is somewhat stable under normal atmospheric conditions.
Its melting point is 1,663°C, its boiling point is 3,402°C, and its density is 9.84g/cm 3 . Characteristics
Lutetium has had a number of different names over the years. At one time or another, it was called neoytterbium, lutecium, lutetia, lutetium, and cassiopium. Some scientists in Germany still refer to it as cassiopium.
Lutetium reacts slowly with water and is soluble in weak acids. Its crystals exhibit strong magnetic properties, which are important to the study of magnetism.