Question

Write the abbreviated electron configuration for each of the following elements. (a) \(\mathrm{Bi}\) (b) Rn (c) \(\mathrm{Ra}\)

Short answer

(a) For \(\mathrm{Bi}\) (bismuth), the abbreviated electron configuration is \([Xe] 4f^{14} 5d^{10} 6s^{2} 6p^{3}\). (b) For \(\mathrm{Rn}\) (Radon), the abbreviated electron configuration is \([Xe] 4f^{14} 5d^{10} 6s^{2} 6p^{6}\). (c) For \(\mathrm{Ra}\) (Radium), the abbreviated electron configuration is \([Rn] 7s^{2}\).

Step-by-step solution

Identify the location of the element on the Periodic Table

Identify where each of the elements (Bi, Rn, and Ra) is located on the Periodic Table. This will help in predicting their electron configurations. This is because the position of an element can help us know in what type of orbital the last electron is placed.

Write the electron configurations

Using the periodic table, count until reaching the element and write down the electron configuration. Use the position of the element to identify the symbol of the noble gas that comes just before it on the periodic table.

Abbreviate the electron configurations

To obtain the abbreviated form of electron configurations, replace the core electrons with the symbol of the noble gas that was identified in the previous step. Put this noble gas in brackets [ ].

Key concepts

Understanding the Periodic Table

The periodic table is a comprehensive chart that organizes all known chemical elements in an informative array. Elements are ordered by increasing atomic number, which is the number of protons in an atom's nucleus. The table is arranged in rows called periods and columns known as groups or families. Each position in the table provides significant information about the properties of the element, including its electron configuration.

Elements within the same column share similar chemical properties due to having the same number of electrons in their outermost shell. This attribute makes the periodic table an essential tool for predicting the behavior of elements in chemical reactions. Electron configuration, a key concept presented in an element’s periodic table listing, details the distribution of electrons in an atom or molecule. It’s essential to understand that the periodic table is founded on quantum mechanics, with each row corresponding to the filling of a different electron shell.

The Role of Noble Gases in Electron Configuration

Noble gases are located in the far right column of the periodic table and are characterized by their extremely low reactivity. This inert behavior arises from the fact that noble gases have a complete outer electron shell, which makes them stable and unlikely to gain or lose electrons. When it comes to writing electron configurations, noble gases offer a convenient shorthand. Instead of writing out the full electron configuration, we can use the configuration of the nearest noble gas with a lower atomic number as a starting point.

For instance, when determining the abbreviated electron configuration, we take the noble gas that precedes our element of interest and use it to represent all the electrons in the filled shells. This simplification is often represented by placing the noble gas's symbol in brackets. Noble gases thus serve as a marker of stability and a reference point for the electron configurations of other elements.

Atomic Structure and Electron Configuration

Atomic structure refers to the arrangement of particles within an atom, which includes a nucleus of protons and neutrons, surrounded by a cloud of electrons in specific regions called orbitals. The arrangement of these electrons is what we call electron configuration. It is crucial for understanding the chemical behavior of an atom since it influences how an element will react with others.

An atom's electron configuration can be depicted in writing, using terms such as '1s', '2s', '2p', and so on, which indicate the energy level and type of orbital the electrons inhabit. The number and arrangement of electrons in these orbitals will follow certain rules, such as the Aufbau principle, the Pauli exclusion principle, and Hund's rule. Mastering the concept of electron configuration allows students to predict bonding patterns and the result of chemical reactions, making it a fundamental aspect of chemistry education. Through the step-by-step process of determining an element's electron configuration, the interconnectedness of the periodic table, noble gases, and atomic structure becomes evident.