Question

The element strontium is used in a variety of industrial processes. It is not an extremely hazardous substance, but low levels of strontium ingestion could affect the health of children. Radioactive strontium is very hazardous, it was a by-product of nuclear weapons testing and was found widely distributed following nuclear tests. Calcium is quite common in the environment, including food products, and is frequently present in drinking water. Discuss the similarities and differences between calcium and strontium, and indicate how and why strontium might be expected to accompany calcium in water supplies, uptake by plants, and so on.

Short answer

In conclusion, calcium and strontium are both Group 2 alkali earth metals with similar properties, such as having two valence electrons, similar atomic radii sizes, and chemical properties. However, there are differences; strontium is heavier, its radioactive isotopes are more hazardous, and it has no known biological function. Due to their similarities, they are found together in water supplies and uptake by plants. Understanding these similarities and differences is crucial in assessing the potential risks of strontium exposure in our environment, as calcium is essential for human health, while even low levels of strontium ingestion could affect a child's health, and radioactive strontium is highly hazardous.

Step-by-step solution

Similarities between Calcium and Strontium

Both calcium and strontium belong to Group 2 of the periodic table, which are alkali earth metals. As a result, they have similar properties: 1. Both have two valence electrons, which makes them form a +2 cation (Ca²⁺ and Sr²⁺). 2. Both have similar atomic radii size and ionic radii size, as they belong to the same group in the periodic table. 3. They have similar chemical properties, as they are both group 2 elements. 4. Both elements are naturally occurring and can exist in water supplies, soil, and ultimately be taken up by plants.

Differences between Calcium and Strontium

Despite the similarities, there are some notable differences between calcium and strontium, such as: 1. Strontium is heavier than calcium, with a larger atomic mass. 2. Calcium is essential for human health, while stable strontium has no known biological function and radioactive strontium is hazardous. 3. Radioactive isotopes of strontium are more dangerous than those of calcium because of their beta emissions and biological accumulation due to similarities with calcium.

Why Strontium accompanies Calcium in water supplies and plants

Since calcium (Ca) and strontium (Sr) have similar chemical properties and sizes, they often substitute for each other in natural environments. For example: 1. Both elements can dissolve in water and form ions (Ca²⁺ and Sr²⁺) that are readily transported in water. 2. They are taken in by plants through similar mechanisms, such as ion channels and transporters. 3. Due to their chemical similarities, many minerals can host both elements together, such as calcite (CaCO₃) and aragonite (SrCO₃).

Conclusion

Although calcium and strontium belong to the same group in the periodic table and exhibit similar chemical properties, their impact on human health is quite different. Calcium is an essential element for human health, whereas strontium at low levels is relatively non-hazardous but can be hazardous to health if radioactive isotopes are ingested. Due to their similarities, they can be found accompanying each other in water supplies, soil, and uptake by plants. This makes understanding the similarities and differences between these two elements critical to evaluate the potential risks of exposure to strontium in our environment.

Key concepts

Similarities between Calcium and Strontium

Calcium and strontium share many similarities because they are both alkali earth metals located in Group 2 of the periodic table. This placement means they both have two valence electrons. As a result, they form ions with a +2 charge, specifically Ca²⁺ and Sr²⁺. This similarity in electron configuration leads to comparable ionic and atomic radii, allowing them to participate in similar chemical reactions. Additionally, both elements naturally occur in water supplies and soil, making them accessible for plant uptake.

Due to their similarities, calcium and strontium might substitute for each other in some natural processes. For example, when absorbed by plants, both elements enter via similar pathways. Water can also carry both ions because they share comparable solubility properties in mineral forms like calcite and aragonite.

In summary, their group placement results in calcium and strontium exhibiting parallel chemical behaviors, leading to their co-existence in various natural environments.

Radioactive Strontium

Radioactive strontium poses significant health hazards. It became well-known as a by-product of nuclear weapons testing. When released into the environment, it spreads widely, integrating into natural systems due to its similarities to calcium. This isotopic form, particularly Strontium-90, emits beta particles, making it dangerously radioactive.

What makes radioactive strontium extremely hazardous is its potential to replace calcium in biological organisms. Because of their similar properties, radioactive strontium can integrate into bones and teeth, where calcium usually resides. Over time, the accumulation of beta-emitting radioactive strontium can cause significant health issues, including an increased risk of cancer.

In essence, understanding the dangers posed by radioactive strontium is crucial, especially its ability to mimic calcium in living organisms. This highlights the need for careful monitoring and management of radioactive materials to protect both human health and the environment.

Biological Function of Calcium

Calcium is essential for a range of biological functions in the human body. It plays a vital role in building and maintaining strong bones and teeth. This element is a critical component of the structural framework that provides strength to these tissues.

Beyond structural roles, calcium is also crucial in cellular functions. It helps with muscle contractions, nerve signaling, and blood clotting. For cells to function properly, calcium ions must flow across cell membranes, acting as important messengers in various physiological processes.

Adequate calcium intake is important for maintaining these essential functions. It supports growth during childhood and continues to prevent the deterioration of bone density in older age. Foods rich in calcium, such as dairy products, leafy greens, and fortified foods, play an important part in ensuring enough calcium is available in the diet.

Overall, calcium is not only vital for structural health but also for maintaining proper cellular functions, emphasizing its importance in overall health and well-being.