Summary
Strontium is a chemical element that belongs to group two of the periodic table. Therefore, strontium falls under alkaline earth metals. It is located just below calcium and its chemical symbol is written as Sr. The element was discovered in the year 1790 by an English scientist named Adair Crawford. Strontium has 26 isotopes, which are atoms of the same element that differ in their mass numbers. Four out of the 26 isotopes (84Sr, 86Sr, 87Sr, and 88Sr) are stable while the rest are unstable. The most notable isotope of strontium is strontium-90 (90Sr), which is produced as an outcome of the nuclear fission of uranium (235U or 238U) or plutonium (239U). The isotopes of strontium differ from the natural form of strontium in radiological properties. This paper looks at the physical, chemical and radiological properties of strontium-90.
Physical Properties
Strontium-90 is a shiny, whitish metal that gets oxidized when exposed to air leading to the formation of a pale yellow coating. Strontium-90 has a molecular weight of 87.62 grams per mole and a density of 2.64 grams per cubic centimeter. Being a group 2 element, strontium-90 has two electrons in its outermost energy shell. To form an ion, it loses these two electrons in an energy-requiring process. The amount of energy required to lose the first electron is 549.2 kJmol -1, whereas 1064 kJmol -1 is needed for the second electron to be lost. Strontium-90 decomposes in water and dissolves in organic solvents such as ethanol. The melting point of 90Sr is 777 oC while its boiling point is 1382 oC. At temperatures of approximately 847 oC, strontium-90 produces a vapor pressure of 5 mmHg.
Chemical Properties
Due to its position in the periodic table, strontium-90 displays a high rate of reactivity. The powdered form of the element ignites without warning and burns vigorously in the air. For this reason, strontium metal is usually stored under kerosene or oil to prevent the reaction with air. Strontium-90 is also capable of reacting with nitrogen and hydrogen to form strontium nitride and strontium hydride. When reacted with dilute acids or cold water, strontium-90 produces hydrogen gas.
Radiological Properties
Strontium-90 is deemed the most dangerous isotope of strontium because of its extremely long half-life of 28.64 years. The activity of 90Sr is 143 Ci per gram. 90Sr decays by beta emission to yield yttrium (90Y), which has a half-life of 64 hours. The process entails decay energy of 0.546 MeV that is shared among the yttrium isotope, an electron and an anti-neutrino. Yttrium subsequently undergoes beta decay with an energy of 2.28 MeV to produce zirconium (90Zr), which is a stable isotope.
The unique radioactive activity of 90Sr makes it a useful element in industrial and medical applications. For, example, it is used to check the width of materials such as metal sheets. In addition, 90Sr is useful in establishing the density of products made from silk and tobacco. In the medical field, 90Sr is employed in the management of pain particularly in malignancies where the conventional drugs produce unpleasant side effects (Henriksen and Maillie 79).
The proximity of strontium to calcium in the periodic table implies that strontium behaves in a similar manner as calcium. When taken into the body, 90Sr accumulates in the bones and teeth. However, its radioactivity causes it to emit radiations that destroy living cells. In the long run, such cells develop cancer.
Works Cited
Henriksen, Thormod and David H. Maillie. Radiation and Health, New York, NY: Taylor & Francis, 2003. Print.