Lawrencium

Lawrencium (Lr)

Introduction

Lawrencium is a synthetic chemical element with atomic number 103 in the periodic table. This man-made radioactive actinide metal has not been detected in Earth’s crust yet. A member of the actinide series in the periodic table, lawrencium has three valence electrons on the outer shell that help element 103 participate in the formation of chemical bonds. 

Fact Box

Chemical and Physical Properties of Lawrencium

The symbol in the periodic table of elements: Lr

Atomic number: 103

Atomic weight (mass): (262) g.mol-1

Group number: Actinides

Period: 7

Color: Presumably metallic and silvery-white or grey

Physical state: Presumably solid at room temperature

Half-life: From 27(+118-13) milliseconds to 11 hours

Electronegativity according to Pauling: Unknown

Density: Unknown

Melting point: Unknown

Boiling point: Unknown

Van der Waals radius: Unknown

Ionic radius: Unknown

Isotopes: 14

Most characteristic isotope: 262Lr

Electronic shell: [Rn] 5f14 6d1 7s2

The energy of the first ionization: Unknown

The energy of the second ionization: Unknown

Discovery date: 1961 by Albert Ghiorso

 

Lawrencium is a transfermium element classified in the periodic table under the symbol Lr, with atomic number 103, and with an assumed atomic mass of (262) g.mol-1. Its electron configuration is [Rn] 5f14 6d1 7s2

 

In the periodic table, this chemical is located to the right of the nobelium, left of the 6d transition metal rutherfordium, and under the lanthanide lutetium. Despite the fact that lawrencium is placed in the d-block, a place designated for the transition metals, the International Union of Pure and Applied Chemistry (IUPAC) classified it as an actinide.

 

The list of chemical properties of this highly radioactive metal is limited to little data. Namely, element 103 has not yet been thoroughly studied due to the minuscule amounts in which it’s produced. However, it’s considered to be chemically similar to the element lutetium and the d-block elements according to research that has been conducted so far. 

 

The first ionization energy of lawrencium was measured in 2015, by using the 256Lr isotope of lawrencium (4.96+0.08−0.07 eV). 

How Was Lawrencium Discovered?

The first forms of lawrencium were produced by two teams of scientists in two independent studies. 

The Discovery of the Berkeley Team (1961)

In 1961, the first atoms of lawrencium were produced at the University of California, Berkeley, United States. While working in the Lawrence Radiation Laboratory (today known as the Lawrence Berkeley Laboratory), a team of scientists led by Albert Ghiorso attempted bombarding a mixture of the longest-lived isotopes of californium (atomic number 98) with boron ions (atomic number 5). This procedure was followed by the acceleration of the ions in a heavy-ion linear accelerator. 

 

As a result, the 258Lr isotope was produced as the very first form of the new element. This form of lawrencium decayed by emitting an 8.6 MeV alpha particle with a half-life of 4.2 seconds.

The Discovery of the Dubna Team (1965)

Several years later, a team of Soviet scientists employed at the Joint Institute for Nuclear Research in Dubna, near Moscow, Russia, led by the Soviet nuclear physicist Georgy Flerov (1913 – 1990), managed to produce the lawrencium-256 isotope, with a half-life of 36 seconds. This was achieved by bombarding an isotope of americium with an isotope of oxygen in 1965. 

 

After lawrencium-126 was produced, the Berkeley team of scientists conducted a study that also included this form of lawrencium. The results of their scientific research showed some of the chemical properties of element 103. Namely, they observed that the properties of lawrencium resemble the tripositive elements in the actinoid series more closely than element 102, nobelium. 

How Did Lawrencium Get Its Name?

Element 103 got its name from the inventor of the cyclotron, Ernest O. Lawrence. This American physicist succeeded in creating a revolutionary research instrument that helped the discovery of several new chemical elements. 

 

The element was named by the researchers upon its discovery, but it was not officialized by the International Union of Pure and Applied Chemistry (IUPAC) until 1997. 

Where Can You Find Lawrencium?

Since lawrencium is a man-made radioactive element produced through nuclear bombardment, it does not occur naturally. This actinide occurs only in strictly regulated scientific lab conditions in extremely small quantities. Lawrencium metal has not been produced yet. 

 

Lawrencium in Everyday Life

This radioactive element has no application in everyday life. It’s used only for the purposes of scientific research. 

How Dangerous Is Lawrencium?

Lawrencium is not considered to have any adverse effects upon health, because its isotopes are very short-lived and unstable. 

Environmental Effects of Lawrencium

Element 103, like all of the transfermium elements, does not occur naturally. Thus, it doesn’t pose any environmental hazard, unless it’s released into the environment through nuclear debris.  

Isotopes of Lawrencium

There are 14 forms of lawrencium with atomic mass numbers ranging from 255 through 260. As lawrencium is a synthetically produced element, there is no standard atomic mass that can be assigned to the substance. 

 

Additionally, since it’s a radioactive element, lawrencium does not have stable isotopes. With a half-life of 11 hours, lawrencium-266 is the longest living radioisotope of this transfermium element. 

 

Lawrencium-262 is the most stable isotope of lawrencium. It has a half-life of 4 hours and decays into:

 

  • Nobelium-262 through an electron capture or spontaneous fission; 
  • Mendelevium-258 through alpha decay.

 

Isotopes of lawrencium have also been traced in the decay processes of heavier chemical elements:

 

  • 294Ts, 290Mc, 286Nh, 282Rg, 278Mt, 274Bh, 270Db decayed to the observed 266Lr isotope;
  • 267Bh, 263Db decayed to the observed 259Lr isotope;
  • 278Nh, 274Rg, 270Mt, 266Bh, 262Db decayed to the observed 258Lr isotope;
  • 261Db decayed to the observed 257Lr isotope;
  • 272Rg, 268Mt, 264Bh, 260Db decayed to the observed 256Lr isotope;
  • 259Db decayed to the observed 255Lr isotope;
  • 266Mt, 262Bh, 258Db decayed to the observed 254Lr;
  • 261Bh, 257Dbg,m decayed to the observed 253Lrg,m isotope;
  • 260Bh, 256Db decayed to the observed 252Lr isotope;
  • 255Db decayed to the observed 251Lr isotope.

 

Nuclide

[n 1]

Z N Isotopic mass (Da)

[n 2][n 3]

Half-life Decay

mode

[n 4]

Daughter

isotope

Spin and

parity

[n 5][n 6]

Excitation energy[n 6]
251Lr[1] 103 148 251.09418(32)# 27(+118-13) ms SF (various)
252Lr[n 7] 103 149 252.09526(26)# 390(90) ms

[0.36(+11−7) s]

α (90%) 248Md
β+ (10%) 252No
SF (1%) (various)
253Lr[n 8] 103 150 253.09509(22)# 580(70) ms

[0.57(+7−6) s]

α (90%) 249Md (7/2−)
SF (9%) (various)
β+ (1%) 253No
253mLr[n 8] 30(100)# keV 1.5(3) s

[1.5(+3−2) s]

(1/2−)
254Lr[n 9] 103 151 254.09648(32)# 13(3) s α (78%) 250Md
β+ (22%) 254No
SF (.1%) (various)
255Lr 103 152 255.096562(19) 22(4) s α (69%) 251Md 7/2−#
β+ (30%) 255No
SF (1%) (various)
256Lr 103 153 256.09849(9) 27(3) s α (80%) 252Md
β+ (20%) 256No
SF (.01%) (various)
257Lr 103 154 257.09942(5)# 646(25) ms α (99.99%) 253Md 9/2+#
β+ (.01%) 257No
SF (.001%) (various)
258Lr 103 155 258.10176(11)# 4.1(3) s α (95%) 254Md
β+ (5%) 258No
259Lr 103 156 259.10290(8)# 6.2(3) s α (77%) 255Md 9/2+#
SF (23%) (various)
β+ (.5%) 259No
260Lr 103 157 260.10551(13)# 2.7 min α (75%) 256Md
β+ (15%) 260No
SF (10%) (various)
261Lr 103 158 261.10688(22)# 44 min SF (various)
α (rare) 257Md
262Lr 103 159 262.10961(22)# 216 min β+ 262No
α (rare) 258Md
266Lr[n 10] 103 163 266.11983(56)# 11 h SF (various)

Source: WIkipedia

 

List of Lawrencium Compounds 

Lawrencium is assumed to adopt the +3 oxidation state since it has three electrons in its valence shell. Also, in an aqueous solution, lawrencium is a trivalent ion. 

 

It can be found in the two following compounds:

 

  • Lawrencium(III) Fluoride LrF
  • Lawrencium(III) Hydroxide Lr(OH)3

5 Interesting Facts and Explanations

  1. Lawrencium was discovered as the 14th and last member of the actinide family of the periodic table. 
  2. Lawrence invented the cyclotron in 1934. It’s an electrically charged device that accelerates electrons between two large electrodes in a constant magnetic field.
  3. Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer, and their colleagues were the team of Berkley scientists who succeeded in producing the first atom of the radioactive element lawrencium.
  4. Element 103 is the heaviest actinide in that family of elements.
  5. Although two different teams succeeded in producing lawrencium isotopes at almost the same time, the IUPAC declared the Berkeley team of scientists as the official discoverers, as they produced the first lawrencium isotope 4 years before the Dubna team.