Question

Identify each of the following elements as a metal, nonmetal, or metalloid: (a) phosphorus, (b) strontium, (c) manganese, (d) selenium, (e) rhodium, (f) krypton.

Short answer

(a) Phosphorus is a nonmetal, (b) Strontium is a metal, (c) Manganese is a metal, (d) Selenium is a nonmetal, (e) Rhodium is a metal, (f) Krypton is a nonmetal.

Step-by-step solution

Identify Phosphorus

Phosphorus can be found in Group 15 (VA) of the periodic table. Elements in this group are nonmetals. Therefore, phosphorus is a nonmetal.

Identify Strontium

Strontium is in Group 2 (IIA) of the periodic table. Elements in this group are alkaline earth metals, which are a type of metal. So, strontium is a metal.

Identify Manganese

Manganese is located in Group 7 (VIIB) of the periodic table. Elements in this group are transition metals, which are a type of metal. Therefore, manganese is a metal.

Identify Selenium

Selenium can be found in Group 16 (VIA) of the periodic table. Elements in this group are nonmetals. Thus, selenium is a nonmetal.

Identify Rhodium

Rhodium is in Group 9 (VIIIB) of the periodic table. Elements in this group are transition metals, which are a type of metal. So, rhodium is a metal.

Identify Krypton

Krypton is located in Group 18 (VIIIA) of the periodic table. Elements in this group are noble gases, which are nonmetals. Therefore, krypton is a nonmetal.

Key concepts

Metals

Metals are found mostly on the left side and in the center of the periodic table.
They are characterized by their ability to conduct heat and electricity, exhibit a shiny luster, and are malleable and ductile. This means that metals can be shaped into sheets (malleability) or drawn into wires (ductility). Most metals also have high melting and boiling points.

• Examples like strontium from the exercise are alkaline earth metals.
• Manganese and rhodium are classified as transition metals.

These sub-categories of metals have unique properties setting them apart from each other in terms of reactivity and stability.

Nonmetals

Nonmetals are located on the upper right side of the periodic table.
Contrary to metals, they are poor conductors of heat and electricity and are not lustrous. Nonmetals can be solid, liquid, or gaseous at room temperature and are not malleable or ductile. In fact, solid nonmetals are generally brittle and will break readily. Nonmetals are diverse in their properties and uses, and they often form compounds with metals.

• In the exercise, phosphorus and selenium are identified as nonmetals.
• Krypton, a noble gas, is also considered a nonmetal.

Metalloids

Metalloids are elements that have properties of both metals and nonmetals.
Located on the periodic table along the stepping line that separates metals and nonmetals, metalloids are semiconductors, which makes them very useful in electronic devices. They are less conductive than metals but more so than nonmetals and have intermediate reactivity.

• Common metalloids include silicon and boron, even though they are not part of the exercise.

While no metalloid was explicitly identified in the exercise, understanding their position on the periodic table is essential for handling classification problems.

Transition Metals

Transition metals are found in the middle of the periodic table in groups 3 through 12.
They are known for their ability to form colorful compounds, their usefulness as catalysts, and their multiple oxidation states. Transition metals are great conductors of electricity and heat, and they have high melting and boiling points. These properties make them essential in various industries and biological systems.

• Manganese and rhodium from the exercise are examples of transition metals.

Alkaline Earth Metals

The alkaline earth metals belong to Group 2 (IIA) of the periodic table.
These metals are highly reactive, but not as reactive as the alkali metals in Group 1. They have two electrons in their outermost energy level. This configuration causes them to readily lose both electrons, making them strong reducing agents.

• Strontium, referenced in the exercise, is an example of an alkaline earth metal.

Noble Gases

Noble gases make up Group 18 (VIIIA) of the periodic table and are known for their lack of reactivity.
This inertness is due to the fact that they have a full outer shell of electrons, which makes them stable and nonreactive under standard conditions. Noble gases are all odorless, colorless, monatomic gases at room temperature. They are used in lighting, welding, and space technology due to their unique properties.

• Krypton, which was identified in the exercise as a nonmetal, is a noble gas.