Problem 23 - Chemistry: An Atoms-Focused Approach

Question

Which of the following properties can be used to distinguish a metallic element from a semimetallic element: atomic radius, electrical conductivity, and/or molar mass?

Step-by-Step Solution

Answer

Answer: Electrical conductivity can be used to distinguish a metallic element from a semimetallic element.

Step 1: Understand Metallic and Semimetallic Elements

First, we must define what a metallic element and a semimetallic element are. Metallic elements are elements that are good conductors of electricity and heat, have a shiny appearance, and tend to be malleable and ductile. Semimetallic elements, also known as metalloids, have properties intermediate between metals and nonmetals. They are often semiconductors, meaning that their electrical conductivity lies between that of metals and nonmetals.

Step 2: Evaluate the Significance of Atomic Radius

Atomic radius is the size of an atom and generally increases down a group and decreases across a period in the periodic table. Since metallic and semimetallic elements can be found in the same group, such as silicon (Si) and germanium (Ge) in Group 14, the atomic radius property cannot reliably distinguish between the two types of elements.

Step 3: Evaluate the Significance of Electrical conductivity

Electrical conductivity is the ability of a material to conduct electricity. Since metals are good conductors, and semimetals (metalloids) have electrical conductivity intermediate to that of metals and nonmetals, electrical conductivity is a property that can be used to distinguish a metallic element from a semimetallic element.

Step 4: Evaluate the Significance of Molar Mass

Molar mass is the mass of a given substance (element or compound) divided by the amount of substance. It is expressed in units of grams per mole (g/mol). Since molar mass depends on the element's atomic number, and both metallic and semimetallic elements can be found within the same group or adjacent groups in the periodic table, molar mass cannot be considered a reliable property for distinguishing between metallic and semimetallic elements.

Step 5: Conclusion

Based on our evaluation of the three given properties - atomic radius, electrical conductivity, and molar mass - the only property that can be effectively used to distinguish a metallic element from a semimetallic element is electrical conductivity.