Cesium

Definition

Cesium is a soft, silvery-white alkali metal that is the most electropositive and reactive of all the stable elements. It is the least dense of the stable elements and has the highest electron affinity of any element, making it highly reactive and prone to forming ionic compounds.

5 Must Know Facts For Your Next Test

1. Cesium has the lowest melting point (28.5°C) and boiling point (678.4°C) of all the stable elements.
2. Cesium is the most electropositive element, meaning it has a strong tendency to lose its valence electron and form positive ions.
3. Cesium is highly reactive and must be stored in an inert atmosphere or sealed container to prevent it from reacting with air, water, or other substances.
4. Cesium is used in atomic clocks, photoelectric cells, and as a catalyst in the production of organic chemicals.
5. Cesium-137 is a radioactive isotope of cesium that is used in medical and industrial applications, but it can also be a dangerous environmental pollutant.

Review Questions

• Explain how the position of cesium on the periodic table relates to its chemical reactivity and physical properties.
  • As an alkali metal in group 1 of the periodic table, cesium has a very low ionization energy and a high tendency to lose its valence electron to form positive ions. This makes cesium highly reactive and electropositive, with low melting and boiling points compared to other elements. The large atomic radius of cesium also contributes to its reactivity, as the valence electron is held more loosely and can be easily donated to form ionic bonds.
• Describe the role of cesium in the development of atomic clocks and other technological applications.
  • The unique properties of cesium, such as its high sensitivity to electromagnetic radiation and the precise frequency of its electron transitions, make it a crucial element in the development of atomic clocks. Cesium atomic clocks use the natural oscillation of cesium atoms to provide an extremely accurate and stable time reference, with applications in GPS, telecommunications, and scientific research. Additionally, cesium is used in photoelectric cells and as a catalyst in the production of organic chemicals, taking advantage of its high reactivity.
• Discuss the potential environmental and health concerns associated with the radioactive isotope cesium-137.
  • Cesium-137 is a radioactive isotope of cesium that can be a dangerous environmental pollutant. If released into the environment, cesium-137 can contaminate soil, water, and food sources, posing a risk to human health through ingestion or exposure. The radioactive emissions from cesium-137 can damage DNA and increase the risk of cancer and other health problems. Proper handling, storage, and disposal of cesium-137 are essential to minimize its environmental impact and potential harm to living organisms.

Related terms

Alkali Metals: The group 1 elements on the periodic table, including lithium, sodium, potassium, rubidium, cesium, and francium, which are highly reactive and have low ionization energies.

Atomic Radius: The distance from the center of an atom to the outermost shell of electrons, which generally increases down a group on the periodic table.

Ionization Energy: The amount of energy required to remove an electron from an atom, which generally decreases down a group on the periodic table.