Problem 129 - Chemistry Matter and Change

Question

Write the symbol and name of the element that fits each description. (Chapter 6\()\) a. the second-lightest of the halogens b. the metalloid with the lowest period number c. the only group 16 element that is a gas at room temperature d. the heaviest of the noble gases e. the group 15 nonmetal that is a solid at room temperature

Step-by-Step Solution

Answer

a. Cl, b. B, c. O, d. Rn, e. P.

Step 1: Identifying the Second-Lightest Halogen

Halogens are elements found in Group 17 of the periodic table. The halogens, ordered by increasing atomic number, are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The second-lightest halogen is chlorine.

Step 2: Finding the Metalloid with the Lowest Period Number

Metalloids have properties of both metals and non-metals and are found along the zig-zag line on the periodic table. They are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). The element with the lowest period on the periodic table is boron, which is in period 2.

Step 3: Identifying the Group 16 Gas at Room Temperature

Group 16 elements are oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). The only gas at room temperature among these is oxygen.

Step 4: Determining the Heaviest Noble Gas

Noble gases are located in Group 18. The noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). The heaviest of these is radon.

Step 5: Finding the Solid Group 15 Nonmetal

Group 15 nonmetals include nitrogen (N), phosphorus (P), arsenic (As), which is actually a metalloid. At room temperature, nitrogen is a gas, while phosphorus is a solid. Thus, the Group 15 nonmetal that is a solid at room temperature is phosphorus.

Key Concepts

Halogens

Halogens belong to Group 17 on the periodic table and are known for their high reactivity.
They include fluorine, chlorine, bromine, iodine, and astatine. These elements have seven valence electrons, making them eager to gain one more electron to achieve a stable electronic configuration.

Some common characteristics of halogens are:

• They are nonmetals.
• Have low melting and boiling points that increase with higher atomic numbers.
• Highly electronegative and reactive, especially with alkali and alkaline earth metals.

Among the halogens, chlorine is the second-lightest. It's a yellow-green gas at room temperature and is commonly used in disinfection and water treatment thanks to its reactivity.

Metalloids

Metalloids exhibit properties of both metals and non-metals.
They bridge the gap between metals and non-metals on the periodic table, positioned along a zig-zag line.

Some of the main metalloids include:

• Boron (B)
• Silicon (Si)
• Germanium (Ge)
• Arsenic (As)
• Antimony (Sb)
• Tellurium (Te)

Boron is the metalloid with the lowest period number, being found in period 2. One interesting property of boron is its ability to form borate crystals and to be used in glassware, electronics, and as a semiconductor.

Noble Gases

Noble gases are the least reactive elements found in Group 18.
These gases have a full set of valence electrons, making them stable and not very reactive under standard conditions.

The noble gases are:

• Helium (He)
• Neon (Ne)
• Argon (Ar)
• Krypton (Kr)
• Xenon (Xe)
• Radon (Rn)

Radon is the heaviest noble gas. It's radioactive and found naturally as a product of the decay of uranium. However, caution is needed as it's a health hazard when inhaled over time.

Group 16 Elements

Group 16, sometimes known as the oxygen group, consists of elements with a diverse range of properties.
This group contains oxygen, sulfur, selenium, tellurium, and polonium.

Characteristic features of Group 16 elements are:

• Six valence electrons.
• They form compounds with metals and nonmetals.
• A tendency to gain or share electrons to achieve a full outer shell.

In this group, oxygen is the only element that is a gas at room temperature. Its presence in Earth's atmosphere is crucial for life, playing a key role in processes like respiration and combustion.