Question

Write the electron configuration for the element fitting each of the following descriptions. a. the metal in group 15 that is part of compounds often found in cosmetics b. the halogen in period 3 that is part of a bleaching compound used in paper production c. the transition metal that is a liquid at room temperature; is sometimes used in outdoor security lights

Short answer

The electron configurations for the elements fitting the given descriptions are as follows: a. Bismuth (Bi): \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^3\] b. Chlorine (Cl): \[1s^2 2s^2 2p^6 3s^2 3p^5\] c. Mercury (Hg): \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10}\]

Step-by-step solution

a. Metal in group 15 that is part of compounds often found in cosmetics.

1. From the description, we can determine that we are looking for a metal in group 15 that is used in cosmetics. The metal in group 15 that fits this description is Bismuth (Bi). 2. Bismuth is the 83rd element in the periodic table, which means it has an atomic number of 83. 3. To write the electron configuration, we use the periodic table and follow the order of filling orbitals. The configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^3\]

b. Halogen in period 3 that is part of a bleaching compound used in paper production.

1. We are looking for a halogen in period 3 that is used as a bleaching agent in paper production. The element that fits this description is Chlorine (Cl). 2. Chlorine is the 17th element in the periodic table, which means it has an atomic number of 17. 3. To write the electron configuration, we again use the periodic table and follow the order of filling orbitals. The configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^5\]

c. Transition metal that is a liquid at room temperature and used in outdoor security lights.

1. We need to find a transition metal that is liquid at room temperature and used in outdoor security lights. The element that fits this description is Mercury (Hg). 2. Mercury is the 80th element in the periodic table, which means it has an atomic number of 80. 3. To write the electron configuration, we use the periodic table and follow the order of filling orbitals. The configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10}\]

Key concepts

The Periodic Table

The periodic table is a master chart of all known elements, each with a unique atomic structure and properties. It's designed with both simplicity and detail in mind, organizing elements into rows called periods and columns known as groups or families.

Elements in the same group share similar chemical characteristics, largely due to their electron configurations. For example, in the exercise, Bismuth (Bi) is identified as a metal in group 15. This means it shares its group with other elements like nitrogen (N), phosphorus (P), arsenic (As), and antimony (Sb), which all have a tendency to form three bonds in compounds, a property reflected in their place in the periodic table.

Furthermore, the periodic table also indicates the element's state at room temperature, whether it’s a solid, liquid, or gas, which is pivotal in identifying Mercury (Hg) in the exercise as the only liquid transition metal at room temperature.

Atomic Number

An element's atomic number is a fundamental property that dictates its position on the periodic table and reveals the number of protons in the nucleus of an atom. Each element has a unique atomic number, making it an identifier as distinct as a fingerprint.

For instance, Chlorine (Cl) has an atomic number of 17, placing it in the 17th spot on the periodic table, and more specifically, as the halogen in period 3. The atomic number directly influences an element's electron configuration because it equals the number of electrons in a neutral atom.

When we look at the electron configuration for Bismuth (Bi), with an atomic number of 83, we know that it has 83 electrons arranged in orbitals around the nucleus. This arrangement is crucial to understanding the element's chemical behavior and is the reason why atomic number is so widely used in chemistry.

Orbital Filling Order

Orbital filling order is the sequence in which electrons populate the orbitals around an atom's nucleus. This progression follows a specific set of rules guided by the principles of quantum mechanics, such as the Aufbau principle, the Pauli exclusion principle, and Hund's rule.

The Aufbau principle suggests that electrons fill orbitals starting with the lowest energy level first. Consequently, the 1s orbital is filled before the 2s orbital, and so on. The exercise showcases this hierarchy with Mercury’s electron configuration beginning with \(1s^2\) and continuing in order of increasing energy levels.

However, there are exceptions to the general filling order due to electron-electron interactions within an atom which can alter energy levels. Understanding the typical order and the exceptions is a major step in mastering the art of writing electron configurations. As students become familiar with orbital filling order, they unlock the ability to predict and explain the chemical behavior of elements based on the structure of their electrons.