Problem 88 - General Chemistry: Principles and Modern Applications

Question

The following electron configurations correspond to the ground states of certain elements. Name each element. (a) \([\mathrm{Ar}] 3 d^{10} 4 s^{2} 4 p^{3} ;\) (b) \([\mathrm{Ne}] 3 s^{2} 3 p^{4} ;\) (c) \([\mathrm{Ar}] 3 d^{1} 4 s^{2}\) (d) \([\mathrm{Kr}] 4 d^{6} 5 s^{2} ;\) (e) \([\mathrm{Xe}] 4 f^{12} 6 s^{2}\)

Step-by-Step Solution

Answer

The corresponding elements are (a) Arsenic (As), (b) Sulfur (S), (c) Scandium (Sc), (d) Molybdenum (Mo), and (e) Lutetium (Lu)

Step 1: Identify Elements

Use the last part of the electron configuration to identify the group and period to which an element belongs. For example, with the electron configuration \([\mathrm{Ar}] 3 d^{10} 4 s^{2} 4 p^{3}\), the last part, or highest energy level, is 4p^3. This shows it belongs to the p-block, specifically Group 15 and period 4. The element with this electron configuration is Arsenic (As).

Step 2: Solve for all

Using the same process, identify all the elements. Here are the elements under each letter: \(a) \([\mathrm{Ar}] 3 d^{10} 4 s^{2} 4 p^{3}\); Arsenic (As) \(b) \([\mathrm{Ne}] 3 s^{2} 3 p^{4}\); Sulfur (S) \(c) \([\mathrm{Ar}] 3 d^{1} 4 s^{2}\); Scandium (Sc) \(d) \([\mathrm{Kr}] 4 d^{6} 5 s^{2}\); Molybdenum (Mo) \(e) \([\mathrm{Xe}] 4 f^{12} 6 s^{2}\); Lutetium (Lu)

Key Concepts

Ground State

The ground state of an atom is the most stable and lowest energy configuration of its electrons. In this state, electrons fill up the available orbitals starting from the lowest energy levels. This order is primarily guided by the Aufbau principle.
Electrons are most stable in the ground state because this configuration minimizes repulsion between electrons while maximizing attraction to the nucleus.
Here are a few key points to consider about ground states:

• Electrons are always arranged in atoms to minimize the total energy of the atom.
• Ground state configurations can be predicted using the periodic table, following a general order dictated by electron sublevels (s, p, d, f).
• In higher excited states, electrons reside in orbitals of higher energy, which are not filled in the atom's ground state.

Understanding ground state configurations is crucial for identifying elements, as each element has a unique electron configuration that defines its chemical behavior.

Periodic Table

The periodic table is an organized chart of all known elements, arranged in rows by increasing atomic number. This format highlights recurring trends in properties, allowing for predictions about element behaviors and bonding patterns.
Each column in the periodic table represents a group with similar chemical properties, while rows represent periods indicating energy levels of electrons.
Some essential features of the periodic table include:

• The table is divided into blocks (s, p, d, f) based on electron configuration sublevels.
• Groups are vertical columns that contain elements with similar valence electron configurations, often dictating similar chemical properties.
• Periods are horizontal rows that illustrate the energy level occupied by the valence electrons.

Using the periodic table, one can deduce the electron configuration of an element and its most stable form, facilitating the understanding of chemical reactivity and bonding.

Electron Configuration Notation

Electron configuration notation is a way of writing the distribution of electrons among the orbitals of an atom. It provides details on the energy levels, sublevels, and the number of electrons in each sublevel.
This notation is essential for understanding how atoms interact in chemical reactions.
Important aspects of electron configuration include:

• The notation uses numbers and letters to describe completed sublevels and electrons within them, such as \(1s^2 2s^2 2p^6\) indicating a complete configuration for Neon (Ne).
• Noble gas shorthand simplifies this notation by representing core electrons with the symbol of the nearest noble gas, as shown in the configurations given in the exercise (e.g., \([\text{Ar}] 3d^{10} 4s^2 4p^3\) for Arsenic).
• The Aufbau principle, Hund's rule, and the Pauli exclusion principle are essential rules governing electron filling order, spin orientation, and occupancy limitations.

Mastering electron configuration notation allows us to predict properties and behaviors of elements, making it a key tool in the study of chemistry.