Problem 102 - Chemistry: The Central Science in SI Units, Global Edition

Question

The explosion of an atomic bomb releases many radioactive isotopes, including strontium-90. Considering the location of strontium in the periodic table, suggest a reason for the fact that this isotope is particularly dangerous for human health.

Step-by-Step Solution

Answer

Strontium-90 is particularly dangerous for human health due to its similar chemical properties to calcium, a biologically relevant element. As an alkaline earth metal, strontium shares the same group with calcium in the periodic table, resulting in the human body mistakenly absorbing it in place of calcium. When incorporated into bones, the radioactive isotope strontium-90 emits ionizing radiation, which can damage DNA, increase cancer risk, and cause long-term health problems.

Step 1: Locate Strontium in the Periodic Table

Strontium (Sr) is found in group 2 and period 5 of the periodic table. Elements in group 2 are called alkaline earth metals.

Step 2: Identify similar elements

Among the alkaline earth metals, calcium(Ca) is the most biologically relevant element. Calcium has the same group as strontium and is directly above it in the periodic table, being in group 2 and period 4.

Step 3: Compare chemical properties

Elements placed in the same group of the periodic table exhibit similar chemical properties. This is because they have the same number of electrons in their outermost (valence) shell. Both strontium and calcium have two valence electrons. Therefore, strontium shares similar chemical properties with calcium.

Step 4: Explain why similar properties make strontium dangerous

Calcium plays a crucial role in human health, specifically in the structure of bones and teeth, as well as nerve and muscle functions. Since strontium has similar chemical properties as calcium, it can be mistakenly absorbed by the human body in place of calcium. The absorption of strontium-90 in place of calcium leads to its incorporation into bones, causing long-term exposure to ionizing radiation within the body.

Step 5: Discuss radioactivity

Strontium-90 is a radioactive isotope, which means it decays and emits ionizing radiation. Ionizing radiation is harmful to living tissue as it can damage DNA, increase the risk of cancer, and cause other long-term health problems.

Step 6: Conclusion

Strontium-90 is particularly dangerous for human health because of its position in the periodic table. Being an alkaline earth metal and sharing similar chemical properties with calcium, strontium-90 can be mistakenly absorbed by the human body and incorporated into bones. As a radioactive isotope, it emits ionizing radiation, leading to long-term health problems and an increased risk of cancer.

Key Concepts

Strontium-90

Strontium-90 is one of the many radioactive isotopes released during the explosion of an atomic bomb. Being a radioactive isotope means it undergoes radioactive decay. This decay is a process where unstable atomic nuclei lose energy by emitting radiation. Strontium-90 decays by emitting beta particles, which are high-speed electron emissions.

In the context of its release in explosive events, such as nuclear bombs, Strontium-90 poses a significant environmental and health risk due to its longevity. It has a half-life of approximately 28.8 years, allowing it to persist in the environment for a long time. Its persistence is a major concern because it can enter living organisms and remain in the body, especially accumulating in bones, leading to prolonged radiation exposure.

Alkaline Earth Metals

Strontium (Sr) belongs to the alkaline earth metals group in the periodic table. This group is in Group 2 and includes beryllium, magnesium, calcium, barium, and radium. Alkaline earth metals are known for having two electrons in their outer valence shell, making them highly reactive, although less so than the alkali metals in Group 1.

These metals are characterized by their shiny luster and low density compared to some other metals. Strontium, like other alkaline earth metals, reacts with water and air but becomes stable over time. The chemical properties of alkaline earth metals like strontium explain why they are easily incorporated into natural processes and living organisms due to their reactivity.

Ionizing Radiation

Ionizing radiation refers to radiation with sufficient energy to remove tightly bound electrons from atoms, thus creating ions. This type of radiation includes alpha particles, beta particles, and gamma rays. Strontium-90, as mentioned earlier, emits beta particles during its decay process.

Exposure to ionizing radiation can be harmful to human health. It can cause damage to living cells, potentially leading to mutations in DNA. This increases the risk of cancer and can cause other serious health issues. When radioactive materials like Strontium-90 are incorporated into the body, the ionizing radiation they emit can continuously damage tissues over time.

Biological Absorption of Elements

The biological absorption of elements refers to the process by which living organisms take up elements from their environment. For humans and other animals, essential elements like calcium are absorbed into the body and used for various physiological functions.

Strontium shares similar chemical properties with calcium due to their position in the same group in the periodic table. As a result, biological systems can mistake strontium for calcium. This is particularly dangerous with Strontium-90, because it can be absorbed and incorporated into human bones in place of calcium.

The ability of Strontium-90 to mimic calcium and be absorbed in bones is why it is so hazardous; it can lead to prolonged exposure to ionizing radiation within the body, particularly affecting bone marrow and thus greatly increasing health risks.