Problem 42 - Chemistry The Central Science

Question

Locate each of the following elements in the periodic table; give its name and atomic number, and indicate whether it is a metal, metalloid, or nonmetal: (a) \(\mathrm{Li},(\mathbf{b}) \mathrm{Sc},(\mathbf{c}) \mathrm{Ge},(\mathbf{d}) \mathrm{Yb}\) \((\mathbf{e}) \mathrm{Mn},(\mathbf{f}) \mathrm{Sb},(\mathbf{g}) \mathrm{Xe}\)

Step-by-Step Solution

Answer

(a) Lithium (Li) has an atomic number of 3 and is a metal. (b) Scandium (Sc) has an atomic number of 21 and is a metal. (c) Germanium (Ge) has an atomic number of 32 and is a metalloid. (d) Ytterbium (Yb) has an atomic number of 70 and is a metal. (e) Manganese (Mn) has an atomic number of 25 and is a metal. (f) Antimony (Sb) has an atomic number of 51 and is a metalloid. (g) Xenon (Xe) has an atomic number of 54 and is a nonmetal.

Step 1: (a) Li

Lithium is represented by the symbol Li. Its atomic number is 3, which means it has three protons in its nucleus. Lithium belongs to the alkali metals family in Group 1, so it is a metal.

Step 2: (b) Sc

Scandium is represented by the symbol Sc. Its atomic number is 21, meaning it has 21 protons in its nucleus. Scandium belongs to the transition metals, located in group 3, hence it is a metal.

Step 3: (c) Ge

Germanium is represented by the symbol Ge. Germanium's atomic number is 32, which means it has 32 protons in its nucleus. Germanium is a metalloid as it shares properties of both metals and non-metals. It is located in group 14.

Step 4: (d) Yb

Ytterbium is represented by the symbol Yb. Its atomic number is 70, meaning it has 70 protons in its nucleus. Ytterbium is a rare earth metal in the Lanthanide series and is a metal.

Step 5: (e) Mn

Manganese is represented by the symbol Mn. The atomic number of Manganese is 25, meaning it has 25 protons in its nucleus. Manganese belongs to the transition metals, located in group 7, hence it is a metal.

Step 6: (f) Sb

Antimony is represented by the symbol Sb. Its atomic number is 51, indicating it has 51 protons in its nucleus. Antimony is a metalloid, as it has properties of both metals and non-metals. Antimony is located in group 15.

Step 7: (g) Xe

Xenon is represented by the symbol Xe. Its atomic number is 54, meaning it has 54 protons in its nucleus. Xenon is a nonmetal belonging to the noble gases group (group 18) as it has a full outer electron shell.

Key Concepts

Atomic Number

In the periodic table, each element is listed with a unique number called the atomic number. This number indicates the number of protons found in the nucleus of an atom. Protons are positively charged particles, and their count determines the identity of the element. For instance, lithium (Li) has an atomic number of 3, which means it has three protons.

Understanding atomic numbers is crucial because:

• It defines the element: No two different elements can have the same atomic number.
• It helps in locating an element in the periodic table.
• Elements are arranged in increasing order of their atomic number in the periodic table, which helps understand their chemical behaviors.

Metals and Nonmetals

The periodic table categorizes elements broadly into metals and nonmetals. The distinction between these two categories helps us predict the properties and uses of elements.

Metals

Metals are typically found on the left side and the middle of the periodic table. They are generally characterized by:

• High electrical and thermal conductivity.
• Malleability and ductility, meaning they can be shaped and drawn into wires.
• Metallic luster, making them shiny in appearance.

Examples include lithium (Li), scandium (Sc), and manganese (Mn).

Nonmetals

Nonmetals, on the other hand, reside on the right side of the periodic table. Their traits often contrast with those of metals, such as:

• Poor conductivity of heat and electricity.
• Being brittle in solid form, not malleable or ductile.
• Lack of metallic luster.

One well-known nonmetal is xenon (Xe), a noble gas with full valence electron shells, giving it inert properties.

Metalloids

Metalloids are the bridge between metals and nonmetals, situated along the zigzag line that divides these two broad categories on the periodic table. These elements exhibit properties of both metals and nonmetals, making them unique.

Characteristics of Metalloids

• They can conduct electricity better than nonmetals but not as well as metals, which is why they are often called semiconductors.
• Metalloids are capable of forming alloys with metals.
• They often have a mixed appearance, sometimes shiny like metals but brittle like nonmetals.

Examples of metalloids include germanium (Ge) and antimony (Sb). These elements are critical in industries, especially in electronics, due to their semiconducting properties.