Question

Locate (a) krypton, (b) strontium, (c) nitrogen, and (d) cobalt in the periodic table. Indicate which categories apply to each: (i) metal, (ii) nonmetal, (iii) transition element, (iv) main group element, and (v) noble gas.

Short answer

Krypton: nonmetal, noble gas, main group; Strontium: metal, main group; Nitrogen: nonmetal, main group; Cobalt: metal, transition.

Step-by-step solution

Locate Krypton on the Periodic Table

Krypton (Kr) is found in Group 18, Period 4 of the periodic table. It is a part of the noble gases group.

Categorize Krypton

Krypton is a noble gas (v) and is classified as a nonmetal (ii), making it a main group element (iv) as well.

Locate Strontium on the Periodic Table

Strontium (Sr) is found in Group 2, Period 5 of the periodic table. It is part of the alkaline earth metals group.

Categorize Strontium

Strontium is a metal (i) and a main group element (iv).

Locate Nitrogen on the Periodic Table

Nitrogen (N) is found in Group 15, Period 2 of the periodic table, within the pnictogens group.

Categorize Nitrogen

Nitrogen is a nonmetal (ii) and a main group element (iv).

Locate Cobalt on the Periodic Table

Cobalt (Co) is located in Group 9, Period 4 of the periodic table. It is part of the transition metals group.

Categorize Cobalt

Cobalt is a metal (i) and a transition element (iii).

Key concepts

Noble Gases

Noble gases are a unique group of elements located in Group 18 of the periodic table. These elements include helium, neon, argon, krypton, xenon, and radon. What sets noble gases apart is their lack of reactivity under standard conditions. This is due to their full valence electron shells, which make them highly stable.
Some key characteristics of noble gases include:

• Colorless and odorless in nature.
• Nonmetals with very low reactivity.
• Exist as monatomic gases at room temperature.

A common application of noble gases is in lighting: neon lights, for instance, owe their vivid colors to the excitation of these elements. Krypton, specifically, is often used in lighting and photography for its bright white light.

Main Group Elements

The main group elements are found in the s and p blocks of the periodic table and include elements from Group 1 (alkali metals) to Group 18 (noble gases). This diverse group comprises metals, metalloids, and nonmetals, giving rise to a wide variety of chemical behaviors and properties.
Key characteristics of main group elements include:

• Varied physical and chemical properties.
• Often exhibit a consistent and predictable pattern of behavior.
• Typically involved in the formation of the most commonly studied compounds.

For example, nitrogen is a crucial main group element found in Group 15. As a nonmetal, it is essential for life, forming the building blocks of DNA and proteins. On the other hand, strontium, a metal in Group 2, is significant for its applications in fireworks and producing glass for color TV screens.

Transition Elements

Transition elements are found in Groups 3 to 12 of the periodic table. These metals are characterized by their ability to form compounds with a wide range of oxidation states, and some can even exist as free unbound ions. They are known for forming colored compounds and displaying catalytic properties, which are essential in industrial processes.
Some defining features of transition elements include:

• Strong metallic characteristics such as high density and high melting points.
• Exhibit magnetic properties.
• Often act as good conductors of electricity.

Cobalt, for instance, is a notable transition metal found in Group 9. It plays a significant role in diverse fields such as medicine and battery production. The vibrant blue color seen in cobalt glass and ceramics adds to its unique qualities and widespread usage.