Question

Identify each of the following atoms on the basis of its electron configuration: a. \(1 s^{2} 2 s^{2} 2 p^{1}\) b. \(1 s^{2} 2 s^{2} 2 p^{5}\) c. \([\mathrm{Ne}] 3 s^{2}\) d. \([\mathrm{Ne}] 3 s^{2} 3 p^{2}\) e. \([\mathrm{Ne}] 3 s^{2} 3 p^{5}\) f. \([\mathrm{Ar}] 4 s^{1}\) g. \([\mathrm{Ar}] 3 d^{6} 4 s^{2}\)

Short answer

A: B, B: F, C: Mg, D: Si, E: Cl, F: K, G: Fe

Step-by-step solution

Understand Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. Each term in the configuration (e.g., \(1s^2\)) represents electrons in specific orbitals.

Know the Order of Orbitals

Electrons fill orbitals in a specific order based on their energy levels: \(1s\), \(2s\), \(2p\), \(3s\), \(3p\), \(4s\), \(3d\), etc.

Identify Atomic Number

Count the total number of electrons (denoted by the superscripts in the electron configuration) to find the atomic number of the element, which corresponds to its position on the periodic table.

Part A: \(1s^2 2s^2 2p^1\)

Sum the electrons: \(1s^2 = 2\), \(2s^2 = 2\), \(2p^1 = 1\). Total: 5 electrons. This corresponds to Boron (B).

Part B: \(1s^2 2s^2 2p^5\)

Sum the electrons: \(1s^2 = 2\), \(2s^2 = 2\), \(2p^5 = 5\). Total: 9 electrons. This corresponds to Fluorine (F).

Part C: \[Ne] 3s^2\)

The configuration begins with Neon (Ne), which is 10 electrons, plus \(3s^2 = 2\). Total: 12 electrons. This corresponds to Magnesium (Mg).

Part D: \[Ne] 3s^2 3p^2\)

The configuration begins with Neon (Ne), which is 10 electrons, plus \(3s^2 = 2\), \(3p^2 = 2\). Total: 14 electrons. This corresponds to Silicon (Si).

Part E: \[Ne] 3s^2 3p^5\)

The configuration begins with Neon (Ne), which is 10 electrons, plus \(3s^2 = 2\), \(3p^5 = 5\). Total: 17 electrons. This corresponds to Chlorine (Cl).

Part F: \[Ar] 4s^1\)

The configuration begins with Argon (Ar), which is 18 electrons, plus \(4s^1 = 1\). Total: 19 electrons. This corresponds to Potassium (K).

Part G: \[Ar] 3d^6 4s^2\)

The configuration begins with Argon (Ar), which is 18 electrons, plus \(3d^6 = 6\), \(4s^2 = 2\). Total: 26 electrons. This corresponds to Iron (Fe).

Key concepts

atomic number determination

Determining the atomic number is the first step in identifying an element based on its electron configuration. The atomic number corresponds to the total number of protons in an atom. Since atoms are neutrally charged, the atomic number also equals the total number of electrons in the atom. By summing up the superscripts in an electron configuration, you can find the total number of electrons, and thus the atomic number. For example, in the electron configuration \(1s^2 2s^2 2p^1\), the sum of the electrons is \(2 + 2 + 1 = 5\). Therefore, the atomic number is 5, which corresponds to the element Boron (B).

orbital filling order

Electrons fill orbitals in an atom in a specific order, known as the Aufbau principle. This principle states that electrons occupy the lowest energy orbitals available. The order is generally as follows: \(1s\), \(2s\), \(2p\), \(3s\), \(3p\), \(4s\), \(3d\), and so on. Each type of orbital can hold a certain number of electrons: \(s\) orbitals can hold 2 electrons, \(p\) orbitals can hold 6 electrons, \(d\) orbitals can hold 10 electrons, and \(f\) orbitals can hold 14 electrons. Knowing the correct order is crucial for correctly writing and interpreting electron configurations.

electron distribution

Electron configuration describes the distribution of electrons among the orbitals in an atom. This distribution determines the chemical properties of an element. Each orbital is denoted by a number and a letter, such as \(1s\), \(2p\), or \(3d\). The superscript number represents the number of electrons in that orbital. For instance, the configuration \(1s^2 2s^2 2p^5\) indicates 2 electrons in the \(1s\) orbital, 2 electrons in the \(2s\) orbital, and 5 electrons in the \(2p\) orbital. By understanding electron distribution, we can predict how an element will react with others.

periodic table elements

The periodic table organizes elements in order of increasing atomic number. Elements in the same column (group) have similar properties because they have the same outer electron configuration. For instance, all elements in Group 1 have a single electron in their outermost \(s\) orbital. This information helps us identify elements quickly. For example, when we see an electron configuration ending in \(4s^1\), we know it's in Group 1. The periodic table is a valuable tool for understanding and predicting the behavior of elements. Using the table alongside electron configurations, we can easily identify elements such as Potassium (K) with a configuration \( [Ar] 4s^1\).