Question

Consider the anion whose charge is \(2^{-}\) and whose electron configuration is identical to that of argon, Ar. What is the symbol for this anion?

Short answer

The symbol for the anion whose electron configuration is identical to that of argon, Ar, and has a 2- charge is \(S^{2-}\).

Step-by-step solution

Identify the element with an atomic number of 16

Since argon has 18 electrons, we need to find the element that has 16 electrons in its neutral state, thus having an atomic number of 16 (which means 16 protons in its nucleus). A periodic table tells us that the element with an atomic number of 16 is sulfur, S.

Determine the electron configuration of the anion

Now that we've identified sulfur as the element to consider, we can determine its electron configuration as an anion with a 2- charge. A neutral sulfur atom has 16 electrons, so our anion would have 18 electrons (16 + 2) due to the 2- charge. This electron configuration would match that of argon.

Identify the symbol for the anion

The element that matches the given criteria is sulfur, S. An anion of sulfur with a 2- charge is represented with the symbol S²⁻.

Key concepts

Electron Configuration

Electron configuration is a way to describe the arrangement of electrons in an atom. Understanding this concept is crucial for identifying elements and their ions. Electrons are arranged in "shells" or "energy levels," each capable of holding a certain number of electrons. These shells are filled from the lowest energy level upward. For example, the first shell can hold up to 2 electrons, while the second can hold up to 8.
When writing an electron configuration, we denote the number of electrons in a shell or subshell by using numbers and letters. For instance:

• The 1s notation represents the first shell, s subshell with 2 electrons.
• Similarly, 2s²2p⁶ would indicate the next level and subshell filled with 8 electrons.

These patterns help us predict properties of elements, such as their reactivity and formation of ions. Understanding electron configurations allows us to identify similarities across periods and groups in the periodic table, connecting these patterns to chemical behaviors.

Sulfur Anion

A sulfur anion is an atom of sulfur that has gained additional electrons, acquiring a negative charge. The neutral sulfur atom has 16 electrons, but when it becomes an anion with a 2- charge (S²⁻), it gains two more electrons, totaling 18 electrons.
This transformation into a sulfur anion typically occurs because it reaches a more stable electronic configuration by completing its outer shell. This extra stability is crucial since atoms prefer having a full outer electron shell, often resembling that of the nearest noble gas.
In chemical reactions, sulfur tends to gain electrons to achieve this stability, forming anions in practical situations. Knowing how anions form helps us understand the nature of compounds these elements make and the changes they undergo during reactions. Deciphering that transition offers insights into why certain chemical reactions occur and how substances are formed.

Argon Electron Configuration

Argon is a noble gas, meaning its electron configuration represents a full outer shell, making it relatively stable and unreactive. Argon's electron configuration is 1s²2s²2p⁶3s²3p⁶. This arrangement indicates that argon has a total of 18 electrons, filling all available positions in its first three energy levels.
When other elements, like sulfur, form anions and rearrange their electrons to match the configuration of argon, they acquire similar levels of stability. This mimicking of electron configurations is a common trend among elements striving for minimum energy states.

• The process essentially makes the reactive element appear like argon, with a stable electron formation seen widely among other elements in the same block of the periodic table.
• Understanding this concept explains why many ions have electron configurations similar to noble gases, which helps students grasp chemical bonding and reactivity.

By studying argon and its stable configuration, you can predict and explain the bonding and stability trends of other elements, enhancing your comprehension of chemical interactions.