Problem 42 - Chemistry and Chemical Reactivity

Question

Here are symbols for five of the seven elements whose names begin with the letter \(\mathrm{B}:\) B, \(\mathrm{Ba}\), \(\mathrm{Bk}\), \(\mathrm{Bi}\), and \(\mathrm{Br}\). Match each symbol with one of the descriptions below. (a) a radioactive element (b) a liquid at room temperature (c) a metalloid (d) an alkaline earth element (e) a Group 5 A element

Step-by-Step Solution

Answer

(a) Bk, (b) Br, (c) B, (d) Ba, (e) Bi.

Step 1: Identify Symbols for Elements

First, let's identify which elements correspond to the given symbols: \( \mathrm{B} \) stands for Boron, \( \mathrm{Ba} \) stands for Barium, \( \mathrm{Bk} \) stands for Berkelium, \( \mathrm{Bi} \) stands for Bismuth, and \( \mathrm{Br} \) stands for Bromine.

Step 2: Radioactive Element

Considering the radioactive element given in the descriptions, \( \mathrm{Bk} \) (Berkelium) is a known radioactive element. Hence, \( \mathrm{Bk} \) matches description (a).

Step 3: Liquid at Room Temperature

Identifying the liquid at room temperature, \( \mathrm{Br} \) (Bromine) is a halogen that is in liquid form at room temperature. Hence, \( \mathrm{Br} \) matches description (b).

Step 4: Identify the Metalloid

Boron (\( \mathrm{B} \)) is classified as a metalloid. Therefore, \( \mathrm{B} \) matches description (c).

Step 5: Alkaline Earth Element

Among the options, Barium (\( \mathrm{Ba} \)) is found in Group 2 of the periodic table, making it an alkaline earth metal. Therefore, \( \mathrm{Ba} \) matches description (d).

Step 6: Group 5 A Element

Bismuth (\( \mathrm{Bi} \)) is placed in Group 5A of the periodic table. Thus, \( \mathrm{Bi} \) matches description (e).

Key Concepts

Boron

Boron is an intriguing element that is found in the metalloid category of the periodic table. Metalloids have properties that fall between metals and nonmetals. Boron is symbolized by the letter "B" and is located in Group 13 of the periodic table, often referred to as the boron group.

Boron has several important uses, ranging from the manufacture of glass and ceramics to the creation of detergents and bleaches. Although it is not found in its pure form in nature, boron compounds like borates and boric acid are quite common.

• Atomic number: 5
• Non-metallic character: shows resemblance to carbon and silicon
• Common compounds: Borax (Na₂B₄O₇·10H₂O) and boric acid (H₃BO₃)

Boron is essential for plant growth, and some studies suggest it may play a role in bone health in humans. Its unique characteristics make it valuable in both biological and industrial applications.

Barium

Barium, represented by the symbol "Ba," is a member of the alkaline earth metals in Group 2 of the periodic table. These metals are known for their reactivity, particularly with water, where they form hydroxides and hydrogen gas.

In its pure form, barium is a silvery-white metal that is soft and can be cut with a knife. It is not found free in nature due to its high reactivity, but rather in combination with other elements. Barium compounds are used in various industrial applications, such as in the production of drilling fluids for oil wells, in the paint industry, and even in the medical field for barium meal tests.

• Atomic number: 56
• Reactivity: Highly reactive, reacts with air and water
• Notable compounds: Barium sulfate (BaSO₄) used in medical imaging

Despite its useful applications, barium, and its compounds can be toxic, so handling with care is essential. Its role as an alkaline earth metal makes it a significant study subject in chemistry.

Berkelium

Berkelium is a fascinating yet highly radioactive element symbolized by "Bk." It belongs to the actinide series on the periodic table, which are heavy metals with large atomic numbers and are mostly synthetic.

Discovered in 1949, Berkelium is named after the city of Berkeley, California, where it was first synthesized. It doesn’t occur naturally and is typically produced in small quantities in nuclear reactors. Due to its radioactivity and short half-life, its primary use is in scientific research, particularly in nuclear chemistry studies.

• Atomic number: 97
• Isotopes: Most stable isotope is Berkelium-247 with a half-life of 1,380 years
• Appearance: Silvery metal in small amounts, rarely isolated

Because of its radioactive nature, berkelium must be handled in specialized facilities. Its role is primarily research-based, and it helps scientists study the properties of actinides and analyze the interactions of nuclear elements.

Bismuth

Bismuth, with the symbol "Bi," is a fascinating element placed in Group 5A of the periodic table. It has the highest atomic number of all stable elements, possessing a unique lustrous, pinkish-silver color.

Bismuth's physical and chemical properties set it apart. It is considered to be more of a post-transition metal and is not very reactive. It is primarily used in pharmaceuticals and cosmetics due to its non-toxic nature, a characteristic that distinguishes it from other heavy metals. Bismuth subsalicylate, for example, is well-known for its use in treating indigestion and diarrhea.

• Atomic number: 83
• Density: Higher than most metals, yet brittle
• Uses: Pepto-Bismol, fire extinguishers, metal alloys

The low toxicity of bismuth and its ability to form vivid, colorful oxide layers make it an element of interest not only for its chemical properties but also for artistic purposes.

Bromine

Bromine, denoted by "Br," is part of the halogen group located in Group 17 of the periodic table. One of its notable characteristics is that it is a reddish-brown liquid at room temperature, making it quite unique among elements.

Bromine's pungent odor and volatility make it distinguishable. It is used in a variety of applications, such as in flame retardants, water purification, and fumigants. It readily reacts with many elements and compounds, which makes it very useful but also requires caution when handling.

• Atomic number: 35
• State: Only nonmetal liquid at room temperature
• Reactivity: Highly reactive, especially with organic substances

Given its potential as a hazardous chemical, bromine should be managed with care, but its versatile applications highlight its importance in modern industry and science.