To determine the correct classification of the element with the electronic configuration \(1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^7, 4s^2\), we need to analyze the configuration step by step. ### Step 1: Identify the Element The given electronic configuration can be broken down as follows: - The \(1s^2, 2s^2, 2p^6\) configuration accounts for the first 10 electrons, which corresponds to Neon (Ne), a noble gas. - The \(3s^2\) and \(3p^6\) add 8 more electrons, bringing the total to 18 electrons, which corresponds to Argon (Ar), another noble gas. - The \(3d^7\) and \(4s^2\) add 9 more electrons, resulting in a total of 27 electrons. Thus, the element with this electronic configuration is Cobalt (Co), which has an atomic number of 27. ### Step 2: Classify the Element Now, let's analyze the options provided: **A. Non-metal** - Non-metals are typically found on the right side of the periodic table and have high electronegativities and ionization energies. They usually do not conduct electricity and are poor conductors of heat. Cobalt, being a metal, does not fit this classification. **B. Metal** - Metals are generally characterized by their ability to conduct electricity and heat, malleability, ductility, and a tendency to lose electrons to form positive ions. Cobalt is indeed a metal, but we need to consider the other options before concluding. **C. Transition element** - Transition elements are defined as the d-block elements in the periodic table, which are characterized by the presence of d electrons. Cobalt, with its \(3d^7\) configuration, falls into this category as it is located in the d-block of the periodic table (specifically in the 3d series). Therefore, this option is correct. **D. Group two element** - Group two elements are known as alkaline earth metals and include elements like Beryllium, Magnesium, Calcium, etc. These elements have their outermost electrons in the s subshell (specifically \(ns^2\)). Cobalt, with its \(3d^7\) and \(4s^2\) configuration, is not in Group 2; it is in Group 9 of the periodic table. Thus, this option is incorrect. ### Conclusion The correct answer is **C. Transition element** because cobalt is a d-block element with partially filled d orbitals, which is the defining characteristic of transition metals. ### Summary of Key Points - The electronic configuration corresponds to Cobalt (Co), which has 27 electrons. - Cobalt is classified as a transition element due to its d-block location and the presence of d electrons. - Non-metals (Option A) and Group two elements (Option D) do not fit the characteristics of cobalt. - While cobalt is also a metal (Option B), the most specific classification is as a transition element. This thorough analysis helps clarify why the correct answer is C and reinforces the understanding of electronic configurations and periodic table classifications.