Question

What is required for an atom to expand its valence shell? Which of the following atoms can expand its valence shell: \(\mathrm{F}, \mathrm{S},\) \(\mathrm{H}, \mathrm{Al}, \mathrm{Se}, \mathrm{Cl} ?\)

Short answer

Atoms that can expand their valence shell are: \text{S, Al, Se, Cl.}

Step-by-step solution

Understand Valence Shell Expansion

Valence shell expansion occurs when an atom can have more than eight electrons in its outermost shell. This is allowed for atoms in or beyond the third period of the periodic table, as they have empty d-orbitals that can accommodate extra electrons.

Identify Atoms That Can Expand Their Valence Shell

Review the position of each given atom in the periodic table: - Fluorine (F) is in the second period.- Sulfur (S) is in the third period.- Hydrogen (H) is in the first period.- Aluminum (Al) is in the third period.- Selenium (Se) is in the fourth period.- Chlorine (Cl) is in the third period.

Determine Which Atoms Can Expand Their Valence Shell

Any atom in the third period or beyond can expand its valence shell due to available d-orbitals.- Fluorine (F) cannot expand its valence shell (second period).- Sulfur (S) can expand its valence shell (third period).- Hydrogen (H) cannot expand its valence shell (first period).- Aluminum (Al) can expand its valence shell (third period).- Selenium (Se) can expand its valence shell (fourth period).- Chlorine (Cl) can expand its valence shell (third period).

Key concepts

Valence Shell

The valence shell is the outermost electron shell of an atom. It is crucial because it determines how an atom can bond and interact with other atoms. Atoms strive to have a full valence shell, typically with eight electrons, a state known as the octet rule. However, some atoms can hold more than eight electrons in their valence shell. This process is called valence shell expansion. It allows certain atoms to form more complex molecules and bonds. Understanding the valence shell helps to explain why certain atoms can participate in unique chemical reactions.

Periodic Table

The periodic table is a chart that organizes all known elements by increasing atomic number. Elements are arranged in rows called periods and columns called groups or families. The periodic table is essential for understanding chemical behavior and properties because it reveals patterns among the elements.
Each period in the periodic table represents the filling of a new electron shell. For example, elements in the third period have electrons in three shells. Starting from the fourth period, elements have additional available d-orbitals.
Elements in periods three and beyond can expand their valence shells because they have these additional d-orbitals. This allows them to hold more than eight electrons, unlike elements in the first and second periods, which cannot expand their valence shells due to the absence of available d-orbitals.

d-Orbitals

d-Orbitals are specific regions around an atom's nucleus where electrons can be found. Starting from the third period of the periodic table, elements can have d-orbitals. These orbitals can hold a maximum of ten electrons. The presence of d-orbitals is crucial for valence shell expansion.
In atoms from the third period onward, the d-orbitals can be used to accommodate extra electrons beyond the usual eight in the valence shell. This capability allows such atoms to form more bonds and larger molecules. Examples of elements with d-orbitals that can expand their valence shells include sulfur (S), chlorine (Cl), and selenium (Se). Understanding d-orbitals is key to grasping the concept of valence shell expansion and predicting the bonding behavior of various elements.