Question

State where in the periodic table these elements appear: (a) elements with the valence-shell electron configuration $n{s}^{2}n{p}^5$ (b) elements that have three unpaired $p$ electrons (c) an element whose valence electrons are $4s^{2}4p^1$ (d) the $d$ -block elements [Section 6.9$]$

Short answer

(a) Elements with the valence-shell electron configuration $n{s}^{2}n{p}^5$ appear in Group 17 (the Halogens) of the periodic table. (b) Elements with three unpaired $p$ electrons can be found in Group 15 (the Nitrogen group) of the periodic table. (c) The element with valence electrons $4s^{2}4p^1$ is Gallium (Ga), which is located in Group 13 and Period 4 of the periodic table. (d) The $d$-block elements belong to Groups 3 to 12 (transition metals) and are located in the center of the periodic table, between the s-block and p-block elements.

Step-by-step solution

Part (a): Elements with electron configuration $n{s}^{2}n{p}^5$

These elements have 2 electrons in the s subshell and 5 electrons in the p subshell of the same energy level, which means they are 1 electron short of completing the p subshell. The element in group 17 of the periodic table (the halogens) have this electron configuration. So, the elements with such configuration are located in Group 17 (the Halogens) of the periodic table.

Part (b): Elements with three unpaired p electrons

Elements with three unpaired p electrons have the electron configuration $n{p}^3$, as each p orbital can hold two electrons with opposite spins. These elements can be found in Group 15 of the periodic table, the Nitrogen group. Group 15 elements, such as nitrogen, phosphorus, and arsenic, are known to have three unpaired p-electrons.

Part (c): Element with valence electrons $4s^{2}4p^1$

The given electron configuration indicates that the element has 2 electrons in the 4s subshell and 1 electron in the 4p subshell. To determine the element's position in the periodic table, we can look at the sum of the superscripts, which is 2 + 1 = 3. This sum represents the number of electrons in the outermost energy level or the group number in the periodic table. Therefore, the element with this electron configuration is in Group 13 and Period 4. After locating this position, we can identify the element as Gallium (Ga).

Part (d): The d-block elements

The d-block elements are the elements whose outermost electron enters the d-subshell. They are located in the center of the periodic table, between the s-block and p-block elements. The d-block elements belong to Groups 3 to 12 and are commonly referred to as transition metals. Examples of d-block elements include iron (Fe), copper (Cu), and gold (Au).

Key concepts

Valence Electron Configuration

Valence electron configuration is crucial for understanding the chemical behavior of elements. It refers to the arrangement of electrons in the outermost shell of an atom, which determines how the element will interact with others. For instance, the configuration $n{s}^{2}n{p}^5$ indicates that an element has two electrons in its s subshell and five in its p subshell. This specific arrangement is characteristic of the halogens, found in Group 17 of the periodic table. These elements are one electron short of a full p subshell, making them highly reactive. Understanding the valence electron configuration helps predict bonding patterns and chemical reactivity.

Halogens

Halogens are a distinctive group of elements located in Group 17 of the periodic table. They include fluorine, chlorine, bromine, iodine, and astatine. These elements are known for their high reactivity, which is largely due to their valence electron configuration of $n{s}^{2}n{p}^5$. With seven valence electrons, halogens are eager to gain an additional electron to achieve a stable octet, similar to the noble gases. This makes them excellent for forming ionic compounds, especially with alkali and alkaline earth metals. In everyday life, halogens are used in disinfectants, bleaches, and as part of compounds in pharmaceuticals.

Nitrogen Group

The nitrogen group, also known as Group 15, comprises elements such as nitrogen, phosphorus, arsenic, antimony, and bismuth. These elements have a typical valence electron configuration of $n{p}^3$, meaning they have three unpaired p electrons. This configuration makes them versatile in forming either three covalent bonds or sometimes even five, depending on the element and its oxidation state. Nitrogen, for example, is fundamental to life, forming the backbone of amino acids and nucleic acids. The ability of these elements to form multiple covalent bonds makes them essential in various biological and industrial processes.

Transition Metals

Transition metals belong to the d-block of the periodic table, spanning Groups 3 to 12. They are unique because their outermost electrons fill the d subshell, often leading to complex electron configurations. Transition metals, like iron, copper, and gold, are characterized by their ability to form multiple oxidation states, making them highly versatile in chemical reactions. They are known for their metallic properties such as conductivity, malleability, and the ability to form colored compounds. These properties are primarily due to the presence of unpaired d electrons. Transition metals play a crucial role in catalysis, electronic devices, and in the synthesis of various compounds across numerous industries.