Problem 53 - Chemistry and Chemical Reactivity

Question

Reviewing the periodic table. (a) Name an element in Group 2 A. (b) Name an element in the third period. (c) Which element is in the second period in Group \(4 \mathrm{A} ?\) (d) Which element is in the third period in Group \(6 \mathrm{A} ?\) (e) Which halogen is in the fifth period? (f) Which alkaline earth element is in the third period? (g) Which noble gas element is in the fourth period? (h) Name the nonmetal in Group 6A and the third period. (i) Name a metalloid in the fourth period.

Step-by-Step Solution

Answer

a) Magnesium, b) Sodium, c) Carbon, d) Sulfur, e) Iodine, f) Magnesium, g) Krypton, h) Sulfur, i) Germanium.

Step 1: Identify Group 2A Elements

The elements in Group 2A of the periodic table are known as alkaline earth metals. These include Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium. So, one element in Group 2A is Magnesium.

Step 2: Identify Elements in the Third Period

The third period of the periodic table includes the elements from Sodium (Na) to Argon (Ar). Therefore, one element in the third period is Sodium.

Step 3: Identify Element in Second Period of Group 4A

Group 4A, or Group 14, includes Carbon, Silicon, Germanium, Tin, and Lead. The second period only contains Carbon from this group, so the element is Carbon.

Step 4: Identify Element in Third Period of Group 6A

Group 6A includes the chalcogens: Oxygen, Sulfur, Selenium, Tellurium, and Polonium. The third period element in this group is Sulfur.

Step 5: Identify Halogen in Fifth Period

The halogens are in Group 7A. In the fifth period, the halogen is Iodine.

Step 6: Identify Alkaline Earth Element in Third Period

The alkaline earth metals in Group 2A include Beryllium, Magnesium, Calcium, and others. Magnesium is in the third period.

Step 7: Identify Noble Gas in Fourth Period

The noble gases are in Group 8A. In the fourth period, the noble gas is Krypton.

Step 8: Identify Nonmetal in Group 6A and Third Period

In Group 6A (chalcogens), Sulfur is the nonmetal located in the third period.

Step 9: Identify Metalloid in Fourth Period

Metalloids have properties of both metals and nonmetals. In the fourth period, Germanium fits this category.

Key Concepts

Chemical Groups

The periodic table is organized into distinct columns called chemical groups. Each group contains elements with similar chemical properties. For instance:

• Group 1A contains the alkali metals like Sodium and Potassium.
• Group 2A, the alkaline earth metals, includes elements such as Magnesium and Calcium.
• Group 7A is known as the halogens, including elements like Fluorine and Chlorine.
• Group 8A features the noble gases such as Helium and Neon. These elements have a full outer electron shell.

Understanding these groups helps you predict how elements will react chemically.

Elements Periods

The horizontal rows on the periodic table are called periods. Each period signifies the number of electron shells in the atoms of the elements. Let's break down a few key points:

• The first period contains Hydrogen and Helium. Both have electrons only in the first shell.
• The second period includes elements from Lithium to Neon, each with electrons in two shells.
• As you move across a period, elements gain a proton in their nucleus and an electron in their outer shell.

Recognizing these patterns aids in understanding the atomic structure of elements.

Alkaline Earth Metals

Alkaline earth metals belong to Group 2A. They are reactive but less so than alkali metals. Key characteristics include:

• Their typical oxidation state is +2, meaning they lose two electrons when forming compounds.
• These elements like Magnesium and Calcium are found abundantly in the Earth's crust.
• They are shiny and silvery-white in appearance.

These metals play vital roles in geology and biology due to their chemical reactivity.

Noble Gases

Noble gases are in Group 8A and are known for their lack of reactivity. This is because they have a full valence electron shell. Important points are:

• They include elements such as Helium, Neon, and Argon.
• Their inert nature makes them useful in applications where reactions are undesirable, such as in light bulbs and neon signs.
• Krypton and Xenon have specialized uses in lighting and medical imaging.

These gases are crucial for various technological applications due to their stability.

Halogens

The halogens are located in Group 7A and are known for their high reactivity. They readily form compounds, especially with metals. Key points include:

• They exist in different states at room temperature: Fluorine and Chlorine are gases, Bromine is a liquid, and Iodine is a solid.
• Their compounds, like sodium chloride (table salt), are essential to life.
• Halogens gain one electron during reactions, resulting in an oxidation state of -1.

Their reactivity and diverse applications make them significant in industrial chemical processes.

Metalloids

Metalloids, positioned between metals and nonmetals, exhibit properties of both categories. They're found along a zigzag line on the periodic table. Notable characteristics include:

• Examples of metalloids are Silicon and Germanium, both essential in the electronics industry.
• They can conduct electricity better than nonmetals but not as well as metals.
• Metalloids have a metallic luster but are brittle like nonmetals.

These unique properties make metalloids integral to semiconductor technology and other applications.