Problem 29 - Chemistry and Chemical Reactivity

Question

Select answers to the questions listed below from the following list of elements whose symbols start with the letter \(\mathrm{C}: \mathrm{C}, \mathrm{Ca}, \mathrm{Cr}, \mathrm{Co}, \mathrm{Cd}, \mathrm{Cl}, \mathrm{Cs}, \mathrm{Ce}\) \(\mathrm{Cm}, \mathrm{Cu},\) and Cf. (You should expect to use some symbols more than once.) (a) Which are nonmetals? (b) Which are main group elements? (c) Which are lanthanides? (d) Which are transition elements? (e) Which are actinides? (f) Which are gases?

Step-by-Step Solution

Answer

(a) Cl; (b) Ca, Cl; (c) Ce; (d) Cr, Co, Cd, Cu; (e) Cm, Cf; (f) Cl.

Step 1: Identify Nonmetals

The nonmetals are elements that typically lack the characteristics of metals and are found on the right side of the periodic table. From the given list, - Chlorine ( Cl ), is a nonmetal.

Step 2: Identify Main Group Elements

Main group elements are found in groups 1-2 and 13-18 of the periodic table. From the list: - Calcium ( Ca ) and Chlorine ( Cl ) are main group elements.

Step 3: Identify Lanthanides

Lanthanides are elements from atomic numbers 57 through 71. They are rare earth metals. From the given list: - Cerium ( Ce ) is a lanthanide.

Step 4: Identify Transition Elements

Transition elements are found in groups 3-12 of the periodic table. From the list: - Chromium ( Cr ), Cobalt ( Co ), Cadmium ( Cd ), Copper ( Cu ) are transition metals.

Step 5: Identify Actinides

Actinides are elements with atomic numbers from 89 to 103 and are usually radioactive. From the given list: - Curium ( Cm ) and Californium ( Cf ) are actinides.

Step 6: Identify Gases

Gases from the periodic table are typically found in the last two groups in their gaseous state under standard conditions. From the list: - Chlorine ( Cl ) is a gas at room temperature.

Key Concepts

Nonmetals

Nonmetals are fascinating elements that contrast sharply with metals, mostly found on the right side of the periodic table. They typically do not conduct electricity well and are poor conductors of heat. Nonmetals are known for their distinct lack of metallic luster and tend to be brittle when solid.
For the list provided, chlorine (Cl) is the nonmetal. Chlorine, a significant industrial element, is found naturally in the form of a diatomic molecule and is known for its high reactivity.

Main group elements

Main group elements encompass the s and p blocks of the periodic table, which includes groups 1 and 2 and groups 13 through 18. These elements play a pivotal role in forming the backbone of chemistry, participating in a wide range of chemical reactions.
From the provided selection, calcium (Ca) and chlorine (Cl) fall into this category. Calcium, an alkaline earth metal, is crucial for biological systems, while chlorine is an essential component of various household and industrial compounds.

Lanthanides

Lanthanides, often referred to as rare-earth elements, include atomic numbers 57 to 71. They are known for their magnetic and phosphorescent properties and are used in various high-tech applications such as magnets and lighting.
In this context, cerium (Ce) is the lanthanide listed. Cerium finds applications in numerous fields, from catalytic converters to glass polishing.

Transition elements

Transition elements are found in the d-block of the periodic table, spanning groups 3 to 12. Characterized by their variable oxidation states and ability to form colored compounds, transition metals are integral in both historical and modern chemistry.
Elements like chromium (Cr), cobalt (Co), cadmium (Cd), and copper (Cu) from our list are transition metals. Each of these elements has its own unique applications, with copper being particularly known for its use in electrical wiring due to its excellent conductivity.

Actinides

Actinides are heavy elements with atomic numbers from 89 to 103. Often radioactive, these elements have applications ranging from nuclear energy to cancer treatment through radiation.
From the exercise, curium (Cm) and californium (Cf) are actinides. These elements, especially californium, are crucial in neutron emission and thus valuable in nuclear reactor initiation and other specialized areas.

Gases

In the context of chemistry, gases are elements or compounds that exist in the gaseous state at room temperature. They are typically located in the last two groups of the periodic table.
Chlorine (Cl) is a unique element often found as a gas. Generally stored as a greenish-yellow diatomic gas, chlorine is widely used in disinfection, and water treatment processes, thanks to its powerful antibacterial properties.