Question

Which elements have these electron configurations? Give both the symbol and the name: (a) \(1 s^{2} 2 s^{2} 2 p^{5}\) (c) \([\mathrm{Ne}] 3 s^{2} 3 p^{4}\) (b) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}\) (d) \([\mathrm{Ar}] 4 s^{2} 3 d^{8}\)

Short answer

a) Fluorine (F), c) Sulfur (S), b) Sodium (Na), d) Nickel (Ni).

Step-by-step solution

Identify Element for Configuration (a)

To find the element with electron configuration of \(1 s^{2} 2 s^{2} 2 p^{5}\), count the total number of electrons which is 9. The element with 9 electrons is Fluorine (F).

Identify Element for Configuration (c)

The electron configuration \([\mathrm{Ne}] 3 s^{2} 3 p^{4}\) starts with neon's (Ne) configuration, which means the element is in the third period of the periodic table. Adding the extra electrons gives a total of 16, which corresponds to Sulfur (S).

Identify Element for Configuration (b)

The configuration \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}\) contains a total of 11 electrons, identifying the element as Sodium (Na).

Identify Element for Configuration (d)

The configuration \([\mathrm{Ar}] 4 s^{2} 3 d^{8}\) indicates an element after Argon (Ar), with two electrons in the 4s subshell and eight electrons in the 3d subshell. Counting up gives us a total of 18 (Ar) + 10 additional electrons, which makes 28. This is the element Nickel (Ni).

Key concepts

Periodic Table

The periodic table is a comprehensive grid that organizes chemical elements based on their atomic numbers, electron configurations, and recurring chemical properties. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Each row is known as a 'period' and each column is known as a 'group'.

Elements in the same group often have similar properties, including the configuration of their outer electrons, which explains the table's division into different blocks, such as s-block, p-block, d-block, and f-block. Understanding the structure of the periodic table is essential for interpreting electron configurations, as it helps identify an element's location and thus predict its chemical behavior.

Electron Configuration Notation

Electron configuration notation is a method used to represent the distribution of electrons among the orbitals of an atom. It is written as a sequence of numbers and letters that denote energy levels, subshells, and the number of electrons in each subshell. For example, in the notation \(1s^2 2s^2 2p^5\), '1s' refers to the first energy level's s orbital, and the superscript '2' represents the two electrons in that orbital. This notation is critical for understanding the electron arrangements of elements, as it provides insights into an element's chemical properties and reactivity.

Elements with a similar terminal electronic configuration may exhibit comparable chemical properties. In advancing through chemistry, correctly interpreting electron configuration notation is a foundational skill that aids in predicting and explaining the behavior of elements.

Chemical Elements Identification

Identifying chemical elements based on their electron configurations is a skill that interlinks the periodic table and electron configuration notation. As seen in the exercise solutions, by knowing the total number of electrons and the type of subshells they occupy, we can establish an element's identity.

For example, the electron configuration \(1s^2 2s^2 2p^5\) indicates 9 electrons. By referring to the periodic table, we can find that the ninth element is Fluorine (F). Similarly, the notation \(\lbrack\mathrm{Ne}\rbrack 3s^2 3p^4\) reveals that the element starts with the electron configuration of Neon (Ne) plus six more electrons, totaling sixteen, which corresponds to Sulfur (S).

This identification is critical in the study of chemistry as it allows students to predict the kind of chemical reactions an element might undergo and understand their placement in the periodic table, directly enhancing the conceptual comprehension of chemical behaviors and reactions.