Problem 59 - Chemistry: An Atoms-Focused Approach

Question

Which groups in the periodic table contain metals with filled valence bands?

Step-by-Step Solution

Answer

Answer: Metals with filled valence bands are scarce but can be found in Group 12, such as zinc (Zn), cadmium (Cd), and mercury (Hg), which are transition metals.

Step 1: Understanding the periodic table

The periodic table is divided into groups (vertical columns) and periods (horizontal rows). Elements in the same group have the same number of electrons in their outermost shell or valence electrons, which determines their chemical properties.

Step 2: Define filled valence bands

Filled valence bands mean that the elements in these groups have no free electrons available in their valence shells. They usually have completely filled s and p orbitals — a stable electron configuration. The most common elements with filled valence bands are the noble gases.

Step 3: Identify the noble gases

Noble gases belong to Group 18 (sometimes called Group 8A or 0) in the periodic table. These elements are known for having completely filled s and p orbitals in their outermost shells. They include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).

Step 4: Recognize metals with filled valence bands

Although noble gases are not considered metals, the question was about which groups contain metals with filled valence bands. It's essential to mention that most metals do not have completely filled valence bands. However, some examples include zinc (Zn) with the electron configuration [Ar] 4s^2 3d^10 which is a transition metal found in Group 12, and cadmium (Cd) and mercury (Hg) with similar electron configurations.

Step 5: Conclusion

Group 18 (noble gases) primarily contains elements with filled valence bands. However, they are not metals. Metals with filled valence bands are scarce but can be found in Group 12, such as zinc (Zn), cadmium (Cd), and mercury (Hg), which are transition metals.

Key Concepts

Valence Electrons

Valence electrons are the electrons located in the outermost shell of an atom. These electrons are crucial because they determine how an element will react chemically with other elements. Most elements strive to have a complete set of valence electrons, which typically means having eight, known as the "octet rule." This desire for a full outer shell is what drives atoms to form bonds, either by sharing, giving, or taking electrons.

• Valence electrons are responsible for the chemical properties of elements.
• In the periodic table, elements in the same group share the same number of valence electrons, leading to similar reactivity.

Understanding valence electrons helps to predict how elements will form compounds and what kind of bonds they will create. For instance, elements with one valence electron, like sodium (Na), are highly reactive because they easily lose that electron to achieve a noble gas configuration.

Noble Gases

Noble gases are a special group of elements that differ from most others in the periodic table. They are found in Group 18 and are known for having completely filled valence bands, meaning their s and p orbitals in the outermost shell are full. This configuration makes them exceptionally stable and largely nonreactive. The noble gases include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).

• The filled valence shell gives noble gases a low tendency to form chemical bonds.
• This makes them ideal for applications requiring non-reactive environments, like lighting and welding.

Noble gases are unique because they naturally satisfy the octet rule without forming bonds. They are often used in scientific research and various industries due to their stability and inert nature.

Transition Metals

Transition metals, found in the d-block of the periodic table, are elements that exhibit a variety of oxidation states and typically have partially filled d orbitals. These metals, like iron (Fe), copper (Cu), and gold (Au), are known for their ability to form colorful compounds and serve as catalysts in chemical reactions. Some transition metals, such as zinc (Zn), cadmium (Cd), and mercury (Hg) in Group 12, actually have filled d orbitals.

• Transition metals are characterized by their high melting points, electrical conductivity, and malleability.
• They often form coordination complexes, contributing to their diverse chemistry.

While most transition metals do not have completely filled valence bands, the filled d orbitals in elements like zinc provide stability, making these elements an exception. This special stability of transition metals affords them unique positions in both biological processes and industrial applications.