Question

Classify each of the following elements as a metal, nonmetal, or metalloid. (Chapter 6) a. molybdenum b. bromine c. arsenic d. neon e. cerium

Short answer

a. Molybdenum: Metal b. Bromine: Nonmetal c. Arsenic: Metalloid d. Neon: Nonmetal e. Cerium: Metal

Step-by-step solution

Identify the element's location on the periodic table

To classify the given elements, we'll determine their location on the periodic table. a. Molybdenum (Mo) - Group 6, Period 5 b. Bromine (Br) - Group 17, Period 4 c. Arsenic (As) - Group 15, Period 4 d. Neon (Ne) - Group 18, Period 2 e. Cerium (Ce) - Group N/A (Lanthanide series), Period 6

Classify based on their properties and location

Based on the location of each element on the periodic table and their properties, we can classify them as metals, nonmetals, or metalloids. a. Molybdenum (Mo) - This element is found in the center of the periodic table and is a shiny, silver-white metal. Thus, Molybdenum is classified as a metal. b. Bromine (Br) - Located in Group 17, which contains the halogens, Bromine is a nonmetal. Bromine is a dark red liquid at room temperature and has low conductivity. Thus, Bromine is a nonmetal. c. Arsenic (As) - Arsenic is located in the p-block of the periodic table and falls within the metalloid category, as it has properties between those of metals and nonmetals. d. Neon (Ne) - Neon is part of Group 18, which contains the noble gases. These elements are nonmetals, and Neon is a colorless, odorless, and insulating gas, so it falls under the nonmetal category. e. Cerium (Ce) - This element belongs to the Lanthanide series, which consists of a group of f-block metals. Cerium is a silvery-white, lustrous metal, so it is classified as a metal.

Key concepts

Metals and Nonmetals

Metals and nonmetals are two major classifications of elements found in the periodic table. These groups differ in characteristics and properties. Metals, such as molybdenum, are typically found on the left-hand side and the center of the periodic table. They are generally shiny, good conductors of heat and electricity, and are often solid at room temperature. Metals are malleable, meaning they can be hammered into thin sheets without breaking. Additionally, they are ductile, which means they can be drawn into wires.

Nonmetals, like bromine and neon, appear on the right side of the periodic table. They exhibit quite contrasting properties to metals. Nonmetals tend to be poor conductors of heat and electricity. Bromine is unique among nonmetals as it is a liquid at room temperature. Most nonmetals, however, are gases or solid at room temperature. They are not shiny and are often brittle when solid, meaning they can easily break or shatter. Nonmetals play a crucial role in various chemical processes and biological systems.

Metalloids

Metalloids are elements that exhibit properties of both metals and nonmetals. They can be found along the "stair-step" line on the periodic table, which separates metals from nonmetals, for example, arsenic. Metalloids are unique due to their intermediate properties. For instance, they can conduct electricity better than nonmetals but not as well as metals. This property classifies them as semiconductors, which makes them valuable in the electronics industry, especially for making computer chips and solar cells.

Arsenic, a classic example of a metalloid, has uses that take advantage of both its metallic and nonmetallic properties. It forms compounds that can serve in agriculture, semiconductors, and as preservatives. Understanding metalloids is important in understanding the diversity of behaviors seen in elements and their utilities.

Lanthanide Series

The Lanthanide series is a group of fifteen metallic elements from lanthanum to lutetium. These elements are located in the f-block of the periodic table and are often referred to as "rare earth metals." Cerium, the element from our original exercise, is a part of this series. These metals are known for their high luster and conductivity. They are often used in the manufacturing of strong magnets, catalysts, and in various alloys to enhance strength and resistance.

The chemistry of lanthanides is complex due to their ability to exhibit variable oxidation states. Even though these are termed "rare earth metals," they are relatively abundant in the Earth's crust but are difficult to extract. Their unique properties are crucial for modern technology, including electronics, optics, and even in medical imaging. Understanding the lanthanides is key to appreciating their role in the advancement of technology.