Problem 89 - Chemistry

Question

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

Step-by-Step Solution

Answer

Electron Configurations: Boron (B): \(1s^22s^22p^1\), Vanadium (V): \(1s^22s^22p^63s^23p^64s^23d^3\), Nickel (Ni): \(1s^22s^22p^63s^23p^64s^23d^8\), Arsenic (As): \(1s^22s^22p^63s^23p^64s^23d^{10}4p^3\), Iodine (I): \(1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^5\), Gold (Au): \(1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^66s^24f^{14}5d^{10}\).

Step 1: Identifying Atomic Number

The first step is to identify the atomic number for each element. We can find these in the periodic table: B (Boron) - 5, V (Vanadium) - 23, Ni (Nickel) - 28, As (Arsenic) - 33, I (Iodine) - 53, Au (Gold) - 79.

Step 2: Writing Electron Configuration for Boron (B)

Boron has an atomic number of 5, so it has five electrons in its neutral state. The electron configuration is \(1s^22s^22p^1\).

Step 3: Writing Electron Configuration for Vanadium (V)

Vanadium has 23 electrons. The electron configuration is \(1s^22s^22p^63s^23p^64s^23d^3\).

Step 4: Writing Electron Configuration for Nickel (Ni)

Nickel has 28 electrons. The electron configuration is \(1s^22s^22p^63s^23p^64s^23d^8\).

Step 5: Writing Electron Configuration for Arsenic (As)

Arsenic has 33 electrons. The electron configuration is \(1s^22s^22p^63s^23p^64s^23d^{10}4p^3\).

Step 6: Writing Electron Configuration for Iodine (I)

Iodine has 53 electrons. The electron configuration is \(1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^5\).

Step 7: Writing Electron Configuration for Gold (Au)

Gold has 79 electrons. The electron configuration is \(1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^66s^24f^{14}5d^{10}\).

Key Concepts

Atomic Number

The atomic number is a fundamental property of every chemical element in the periodic table. It represents the number of protons in an atom's nucleus. Since protons carry a positive charge, the atomic number also indirectly tells us the number of electrons in a neutral atom, because the atomic charges balance each other. Each element in the periodic table is arranged according to its atomic number, starting with hydrogen, which has an atomic number of 1.

For example, the atomic number of Boron (B) is 5, meaning it has 5 protons and, in its neutral state, 5 electrons. Understanding atomic numbers is essential for writing electron configurations, which map out where these electrons are located around the atom.

Ground-State Electrons

Electrons in an atom exist in different energy levels, also known as shells, surrounding the nucleus. The term "ground-state electrons" refers to the arrangement of electrons around the nucleus where they are at the lowest possible energy levels.

When writing the ground-state electron configuration, we fill up the lowest energy levels first before moving to higher energy ones. This is based on the Aufbau principle. For instance, in a boron atom with an atomic number of 5, the ground-state electron configuration is expressed as \(1s^2 2s^2 2p^1\), meaning there are 2 electrons in the 1s level, 2 in the 2s level, and 1 in the 2p level, filling the lower energy levels before going to higher ones.

Understanding this helps us predict how atoms interact in chemical reactions, as electrons in higher energy levels are more easily involved in bonding.

Periodic Table

The periodic table is a masterpiece of organized chemical knowledge. It lists all known elements in order of increasing atomic number, often divided into groups and periods.

• **Groups**: Vertical columns, contain elements with similar chemical properties because they have the same number of electrons in their outer shell.
• **Periods**: Horizontal rows, indicate the number of electron shells in the atoms.

With this systematic layout, the periodic table helps us quickly deduce an element's electron configuration, determine its chemical properties, and understand its relatedness to other elements.
For instance, nickel (Ni) is found in the 4th period and 10th group; this placement helps determine its electron configuration as \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8\). By referring to its position, we can infer that nickel has partially filled d-orbitals characteristic of transition metals.

Neutral State Elements

Elements in their most natural and stable form are typically in a neutral state, meaning they have an equal number of protons and electrons. This balance results in a net charge of zero, maintaining the electrical neutrality of the atom.

When identifying an element's electron configuration, we assume it is in this neutral state unless otherwise specified. The electron configurations we write, such as for iodine (\(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^5\)), are based on knowing the number of electrons that balance the positive charges from the protons.

A clear understanding of neutral state elements is essential in chemistry, particularly for predicting how atoms will bond with each other since their natural aim is often to achieve a stable, electrically neutral state through gaining, losing, or sharing electrons.