Question

Write the ground-state electron configurations for the following elements: \(\mathrm{B}, \mathrm{V}, \mathrm{Ni}, \mathrm{As}, \mathrm{I}, \mathrm{Au}\).

Short answer

The ground-state electron configurations for the elements are: \(B: 1s^{2}2s^{2}2p^{1}\), \(V: 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\), \(Ni: 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{8}\), \(As: 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{3}\), \(I: 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}\), and \(Au: 1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{1}4f^{14}5d^{10}\).

Step-by-step solution

Understanding the Rules

Electrons in an atom are organized into shells, subshells, and orbitals. Electrons fill up shells and subshells in an order defined by the energy level and shape of the orbital. This filling order is represented by the arrows in the Aufbau diagram.

Writing Electron Configurations For B

To write electron configurations, follow the aufbau diagram from the lowest energy level to the highest. For \(B\) (Boron), which has 5 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{1}\).

Writing Electron Configurations For V

For \(V\) (Vanadium), which has 23 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\)

Writing Electron Configurations For Ni

For \(Ni\) (Nickel), which has 28 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{8}\)

Writing Electron Configurations For As

For \(As\) (Arsenic), which has 33 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{3}\).

Writing Electron Configurations For I

For \(I\) (Iodine), which has 53 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}\).

Writing Electron Configurations For Au

For \(Au\) (Gold), which has 79 electrons, the electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{1}4f^{14}5d^{10}\).

Key concepts

Ground-state electron configurations

The ground-state electron configuration of an element describes how the electrons are distributed among the various atomic orbitals. It's like a map showing the positions of all the electrons in an atom when it's in its lowest energy state. Each element has a unique electron configuration, which can be determined using specific rules and principles.

The configuration is written in a sequence of numbers and letters that represent the energy levels, subshells, and the number of electrons in those subshells. For instance, the electron configuration for Boron (\(\mathrm{B}\)) is \(1s^{2}2s^{2}2p^{1}\). This tells us:

• The 1s subshell contains 2 electrons.
• The 2s subshell also contains 2 electrons.
• There is 1 electron in the 2p subshell.

Writing electron configurations, especially for more complex elements, relies on understanding the order in which electrons fill these orbitals, as well as adhering to certain principles that dictate this filling.

Aufbau principle

The "Aufbau principle" is a German term meaning "building up." It explains the sequence in which electrons fill the atomic orbitals. According to this principle, electrons fill orbitals starting at the lowest available energy levels before moving to higher ones.

The principle follows a specific sequence that can be visually represented in an "Aufbau diagram." This diagram shows the order of filling from lower to higher energy orbitals:

• 1s
• 2s, 2p
• 3s, 3p
• 4s, 3d, 4p (and continues in this pattern)

For example, when writing the electron configurations for \(\mathrm{V}\) (Vanadium), with 23 electrons, electrons fill up the 1s, 2s, 2p, 3s, 3p, 4s, and begin filling the 3d orbitals as its energy increases.\(1s^{2}2s^{2}2p^{6}\) fills first, followed by \(3s^{2}3p^{6}4s^{2}3d^{3}\). Adhering to the Aufbau principle ensures that electrons fill the correct orbitals in the correct order.

Electron orbitals

Electron orbitals are regions around the nucleus of an atom where electrons are most likely to be found. These orbitals have different shapes and sizes, and each type of orbital corresponds to a specific subshell:

• s-orbitals (spherical)
• p-orbitals (dumbbell-shaped)
• d-orbitals (complex shapes)
• f-orbitals (even more complex shapes)

Each kind of orbital can hold a different number of electrons:

• An s-orbital can hold up to 2 electrons.
• p-orbitals can hold up to 6 electrons (across three different orientations).
• d-orbitals can hold up to 10 electrons (spread over five orientations).
• f-orbitals can hold up to 14 electrons (across seven orientations).

Understanding electron orbitals helps in visualizing where electrons are likely to be located and how they interact within the atom. For instance, in \(\mathrm{Ni}\) (Nickel), electrons populate orbitals up to the 3d subshell, \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{8}\), involving s and d orbitals. In more complex atoms, like \(\mathrm{Au}\) (Gold), electrons fill even higher energy orbitals such as 4f and 5d.