Little is known about the properties of astatine, At, because of its rarity and high radioactivity. Nevertheless, it is possible for us to make many predictions about its properties. (b) Would you expect At to be a metal, nonmetal, or metalloid? Explain.

Key Concepts

Periodic Trends

Periodic trends refer to the predictable patterns in the properties of elements as you move across or down the periodic table. These trends include atomic size, ionization energy, and electronegativity, which help in predicting whether an element is likely to behave as a metal, nonmetal, or metalloid based on its position in the table.

Metallic Character

Metallic character describes the tendency of an element to exhibit properties typical of metals, such as conductivity, malleability, and luster. Generally, metallic character increases as you move down a group in the periodic table and decreases across a period from left to right, influencing whether an element like astatine is expected to be metallic.

Radioactivity and Stability

Radioactivity refers to the process by which unstable atomic nuclei lose energy by emitting radiation. Astatine is highly radioactive, which affects its stability and the types of chemical bonds it can form. Understanding the implications of radioactivity is crucial for predicting the behavior of astatine in chemical reactions and its classification as a metal, nonmetal, or metalloid.