Question

Which of elements \(1-36\) have two unpaired electrons in the ground state?

Short answer

The element from \(1-36\) that has two unpaired electrons in its ground state electron configuration is Titanium (Ti, Z=22) with the configuration [Ar] 3d^2 4s^2.

Step-by-step solution

Understanding Unpaired Electrons

Unpaired electrons are those that occupy an atomic orbital without another electron paired with it. In an electron configuration, each orbital can hold up to 2 electrons, having opposite spin (one spin up and one spin down). An unpaired electron is the one that does not have another electron with the opposite spin in the same orbital. These electrons play a significant role in determining the chemical reactivity and magnetic properties of an element.

Writing Down the Periodic Table Blocks

Elements are arranged in the periodic table in blocks of s, p, d, and f, where each block represents the type of atomic orbitals being filled. To find the elements with two unpaired electrons in the ground state, we need to know which block the elements belong to and their electron configurations. From element 1 to 36, we have: - s-block: Elements 1 to 2 (H and He) and 3 to 10 (Li to Ne) - p-block: Elements 11 to 18 (Na to Ar) - d-block: Elements 19 to 36 (K to Kr)

Identifying Elements with Two Unpaired Electrons

Using the above information, we can find the elements with two unpaired electrons by analyzing their electron configurations: 1. Hydrogen (H) has only 1 electron in 1s orbital, i.e., 1 unpaired electron (1s^1). 2. Helium (He) has 2 electrons in the 1s orbital, so both are paired (1s^2). 3. Lithium (Li) to Neon (Ne) (s-block): These elements fill only s and p orbitals and have either 0 or 1 unpaired electrons. 4. Sodium (Na) to Argon (Ar) (p-block): These elements fill only s and p orbitals and also have either 0 or 1 unpaired electrons. 5. Potassium (K) and Calcium (Ca) (d-block): They have 1 unpaired electron (4s^1 and 4s^2, respectively). Now, we need to examine the remaining d-block elements, which are elements from Scandium (Sc) to Krypton (Kr). These elements start filling the d orbitals, and we need to find the elements having two unpaired electrons in their ground state configuration. 6. Scandium (Sc, Z=21) has an electron configuration of [Ar] 3d^1 4s^2, so it has only 1 unpaired electron. 7. Titanium (Ti, Z=22) has an electron configuration of [Ar] 3d^2 4s^2, which has 2 unpaired electrons. 8. Vanadium (V, Z=23) has an electron configuration of [Ar] 3d^3 4s^2, which has 3 unpaired electrons. 9. Chromium (Cr, Z=24) to Krypton (Kr, Z=36) also have more than 2 unpaired electrons or fully paired electrons. So, the only element from 1 to 36 that has two unpaired electrons in its ground state electron configuration is Titanium (Ti).

Key concepts

Electron Configuration

Electron configuration is a way to represent the arrangement of electrons around the nucleus of an atom. Electrons are organized in orbitals, which are regions around the nucleus where there is a high probability of finding an electron. Each orbital can hold a maximum of two electrons with opposite spins: one with spin-up and one with spin-down. This is in accordance with Pauli's exclusion principle.

In writing electron configurations, orbitals are filled in a specific order, beginning with the lowest energy levels. This order is typically given by the Aufbau principle. For example, after the 1s orbital is filled, electrons will fill the 2s orbital, then the 2p orbitals, and so on. Understanding electron configurations is critical, as they help predict the chemical, electronic, and magnetic behavior of elements.

• Each element has a unique configuration that influences its position in the periodic table.
• The number of unpaired electrons can influence an element's magnetism and reactivity.
• The configuration helps explain why certain elements attract or repel each other or why they conduct electricity.

Periodic Table Blocks

The periodic table is divided into blocks—s, p, d, and f—based on the type of atomic orbitals that are being filled by electrons. This block-wise categorization is integral to understanding how electrons populate different energy levels.

• s-block elements include groups 1 and 2, and the filled orbitals are of type s. These elements are typically metals with relatively low electronegativity.
• p-block elements contain groups 13 to 18, with p orbitals being populated. These include non-metals, metalloids, and poor metals.
• d-block elements, also known as transition metals, are found in groups 3 to 12, where d orbitals are filled. They have complex electron arrangements that allow for various oxidation states.
• f-block elements, although not mentioned in the problem, include the lanthanides and actinides.

Understanding these blocks is essential for predicting the properties and reactivities of elements, as elements in the same block often exhibit similar characteristics.

d-block Elements

d-block elements, commonly referred to as transition metals, are characterized by the filling of d orbitals. These elements are located in groups 3 to 12 of the periodic table. They are frequently highlighted for their ability to have various oxidation states and form colored compounds.

Transition metals have unique properties that make them crucial for various industrial applications. For example, they can conduct electricity and heat exceptionally well. Their unpaired d electrons allow these metals to bond with a variety of ligand types in different geometries, which provides them with extensive catalytic capabilities.

Titanium (Ti), as a specific example from the d-block, illustrates some of these traits. Its electron configuration is \[\text{[Ar]} \, 3d^2 \, 4s^2\], which includes two unpaired electrons. This makes Titanium not only a catalyst but also a strong yet lightweight component used in aerospace and medical industries.

Understanding d-block elements' electron configurations helps in determining their magnetic properties and tendencies to form compounds.