Question

In what main group(s) of the periodic table do elements have the following number of half-filled p-orbitals in the outermost principal energy level? (a) 0 (b) 1 (c) 2 (d) 3

Short answer

Question: Identify the main group(s) in the periodic table where elements have the following number of half-filled p-orbitals in their outermost principal energy level: (a) 0, (b) 1, (c) 2, (d) 3. Answer: (a) 0 half-filled p-orbitals: Group 2 and Group 18 (b) 1 half-filled p-orbitals: Group 13 (c) 2 half-filled p-orbitals: Group 14 (d) 3 half-filled p-orbitals: Group 15

Step-by-step solution

Identify the number of outer electrons

For the elements with 0 half-filled p-orbitals in the outermost principal energy level, there should be no electrons (0) or completely filled p-orbitals (6 electrons) in the outer energy level.

Identify the main group in the periodic table

The elements having no half-filled orbitals in the outermost principal energy level are those in Group 2 and Group 18. Group 18 has completely filled p-orbitals, and Group 2 has no p-electrons in the outer shell. (b) 1 half-filled p-orbitals

Identify the number of outer electrons

For the elements with 1 half-filled p-orbitals in the outermost principal energy level, there should be three electrons (3) in the outer p-orbitals.

Identify the main group in the periodic table

The elements with 1 half-filled p-orbitals in the outermost principal energy level belong to Group 13. Group 13 has 3 p-electrons in the outer shell. (c) 2 half-filled p-orbitals

Identify the number of outer electrons

For the elements with 2 half-filled p-orbitals in the outermost principal energy level, there should be four electrons (4) in the outer p-orbitals.

Identify the main group in the periodic table

The elements with 2 half-filled p-orbitals in the outermost principal energy level belong to Group 14. Group 14 has 4 p-electrons in the outer shell. (d) 3 half-filled p-orbitals

Identify the number of outer electrons

For the elements with 3 half-filled p-orbitals in the outermost principal energy level, there should be five electrons (5) in the outer p-orbitals.

Identify the main group in the periodic table

The elements with 3 half-filled p-orbitals in the outermost principal energy level belong to Group 15. Group 15 has 5 p-electrons in the outer shell.

Key concepts

Periodic Table Groups

The periodic table is a tabular arrangement of elements, organized into periodic table groups or families based on similar properties. Specifically, groups run vertically, and elements within the same group typically have the same number of electrons in their outermost shell, which is crucial for chemical bonding and reactivity.

For instance, Group 2 contains the alkaline earth metals, characterized by having two electrons in their outer shell. These are not prone to having half-filled p-orbitals. Conversely, Group 18 includes the noble gases, which are known for having full outer shells, with p-orbitals completely filled with six electrons, and thus are very stable and typically nonreactive.

Understanding how groups in the periodic table relate to the configuration of p-orbitals in the outermost principal energy level helps students anticipate the chemical properties of an element, such as reactivity and the types of bonds it may form.

Electron Configuration

The concept of electron configuration refers to the distribution of electrons in an atom or molecule. Specifically, it describes how the electrons are structured around the nucleus into various energy levels and sublevels, including the s, p, d, and f orbitals.

For p-orbitals, understanding the electron configuration involves recognizing that each p-orbital can hold a maximum of two electrons and that these orbitals begin filling up with electrons after the s-orbital is filled. A half-filled p-orbital, therefore, has just one electron. In the context of our exercise, elements with one, two, and three half-filled p-orbitals correspond to different groups. Group 13 elements, for example, have an electron configuration that results in one half-filled p-orbital in their valence shell, indicative of three p-electrons.

Principal Energy Level

A key term in understanding atoms is the principal energy level. These levels are represented by the quantum number 'n' and can be thought of as the 'shells' or 'layers' that surround the nucleus of an atom. Electrons within an atom are organized into these principal energy levels, and the energy level furthest from the nucleus is known as the valence shell.

As the principal energy level increases, so does the orbital size and energy. The p-orbitals start at the second principal energy level (n=2) and expand with every subsequent level. In our exercise, elements in different groups have a varying number of electrons occupying the p-orbitals within the outermost energy level. For example, Group 14 elements have four valence electrons, occupying the p-orbitals to create two half-filled p-orbitals in the outer shell.

Understanding the arrangement of electrons within these principal energy levels is fundamental to mastering concepts in chemistry, as it directly corresponds to the element's chemical behavior.