Question

Use the periodic table to determine the element corresponding to each electron configuration. $$ \begin{array}{ll}{\text { a. }[\mathrm{Ar}] 4 s^{2} 3 d^{10} 4 p^{6}} & {\text { b. }[\mathrm{Ar}] 4 s^{2} 3 d^{2}} \\ {\text { c. }[\mathrm{Kr}] 5 s^{2} 4 d^{10} 5 p^{2}} & {\text { d. }[\mathrm{Kr}] 5 \mathrm{s}^{2}}\end{array} $$

Short answer

a. Zn (Zinc), b. Ti (Titanium), c. Sn (Tin), d. Sr (Strontium)

Step-by-step solution

Identify Noble Gas Core

The electron configuration starts with the noble gas in brackets which represents the electron configuration for that noble gas. For a., the core is [Ar], which is Argon; for b., it is also Argon; for c., the core is [Kr], which is Krypton; and for d., it is also Krypton.

Add Electrons Beyond Noble Gas Core

Count the number of electrons added beyond the noble gas core. For a. there are 18 electrons added beyond the Argon core, giving it the full electron configuration for Zn (Zinc). For b. there are 2 electrons beyond Argon, it corresponds to Ti (Titanium). For c. there are 14 electrons beyond Krypton, which leads to Sn (Tin). For d. there are 2 electrons beyond Krypton, which corresponds to Sr (Strontium).

Determine Element on Periodic Table

Match the total electron count to the atomic number on the periodic table to identify the element. For a. Argon's atomic number is 18 and 18 additional electrons would make 36, leading to Kr (Krypton), but since the configuration is completed, it represents the element directly above it in the periodic table which is Zn (Zinc). For b. with 22 total electrons, the element is Ti (Titanium). For c. Krypton's atomic number is 36 plus 14 additional electrons totaling 50, which is Sn (Tin). For d. with 38 total electrons, the element is Sr (Strontium).

Key concepts

Understanding the Periodic Table

The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configurations, and recurring chemical properties. This structure reflects periodic trends, such as elements with similar behavior in the same column. It also provides a useful framework for analyzing chemical behavior and is widely used in chemistry, physics, and other sciences.

Each element is listed by its chemical symbol and has a unique place in the periodic table. The table is divided into periods (rows) and groups (columns). Elements with the same number of valence electrons are found in the same group, and their properties are similar. The periodic table also makes it possible to predict the properties of new elements and the types of chemical reactions that elements are likely to undergo. When using the periodic table to determine the element corresponding to a specific electron configuration, it's essential to comprehend how to navigate this tool efficiently.

The Role of a Noble Gas Core in Electron Configuration

Electron configuration refers to the distribution of electrons of an atom or molecule in atomic or molecular orbitals. The 'noble gas core' is an important concept because it simplifies writing out the full electron configuration of an element. This is done by starting with the electron configuration of the nearest noble gas that precedes the element in question, shown in brackets. Noble gases are the elements found in Group 18 (formerly Group 0) of the periodic table and are characterized by having a full set of electrons in their outer shell, which makes them particularly stable.

Noble gas core notations shorthand the configuration of the more complex atoms, making it easier to identify the remaining valence electrons that determine the element's chemical properties. When elements are represented by using their noble gas cores, as seen in the exercise with notations like [Ar] for Argon and [Kr] for Krypton, it allows us to quickly recognize the electron configuration while considering the element's previous stable state.

Atomic Number and Identifying Elements

An element's atomic number is the number of protons found in the nucleus of an atom of that element. It is a unique identifier for each element and dictates the element's position on the periodic table. The atomic number is significant because it not only represents the number of protons but also the number of electrons in a neutral atom. This correlates directly to the element's chemical properties and its electron configuration.

To identify an element based on its electron configuration, you match the total number of electrons to the atomic number on the periodic table. For example, if you have a configuration that ends with 4p^6, you know that the atom has a full outer p subshell, indicating a noble gas. The last digit or the sum of the last electrons added beyond the noble gas core helps you pinpoint the exact element when cross-referenced with the periodic table, as seen in the step by step solutions initially provided.