Question

Which elements have five electrons in the highest-energy \(p\) sublevel in their ground state?

Short answer

The elements that have five electrons in the highest-energy p sublevel in their ground state are elements in Group 17 (or 7A) of the periodic table, which are the halogens: Fluorine, Chlorine, Bromine, Iodine, and Astatine.

Step-by-step solution

Understand Orbital Sublevels

Electron configuration represents the arrangement of electrons within the atomic structure. Each electron is placed in orbitals, which are grouped together in sublevels (s, p, d, f) based on the energy level and the shape. The s sublevel has one orbital, which can hold two electrons, while the p sublevel has three orbitals, which can hold up to six electrons.

Five Electrons in p Orbital

We are looking for elements that have 5 electrons in the highest-energy p sublevel in their ground state. This situation corresponds to the p orbital being filled by 5 electrons. Elements that have this electron configuration end in 'p5'.

Identify Elements

Looking at a periodic table and following the Aufbau Principle, the elements that fit this criteria (5 electrons in the p orbital of its highest energy level) in their ground state are elements that are in group 17 (sometimes referred to as Group 7A following older nomenclature), one spot from the rightmost column. These elements include Fluorine, Chlorine, Bromine, Iodine, and Astatine. These are known as halogens.

Key concepts

Orbital Sublevels

Understanding orbital sublevels is fundamental to grasping how electrons are arranged within an atom. An atom's electron configuration is structured in layers of energy, with electrons filling orbitals in a manner that minimizes the energy of the atom. There are four types of sublevels — s, p, d, and f — each with a varying number of orbitals.

The s sublevel contains a single orbital, the p sublevel contains three orbitals, the d sublevel has five, and the f sublevel holds seven. Each orbital can hold a maximum of two electrons. Therefore, s can accommodate 2 electrons, p can carry 6, d can fit 10, and f has room for 14 electrons. The p sublevel has a dumbbell shape and its three orbitals are spatially oriented at right angles to each other.

P Sublevel Electrons

Focusing on the p sublevel, we find that it can house up to six electrons, two in each of its three orbitals. These p sublevel electrons play a crucial role in determining the chemical properties of an element. When we reference elements with five electrons in the p sublevel, we are describing an almost filled p sublevel — one that has just one orbital with a single electron while the other two orbitals are fully filled.

This specific arrangement can significantly affect an element's reactivity and its tendency to bond with other elements. In the case of the exercise, elements with five p sublevel electrons are one electron short of having a completely filled outer shell, which drives their high reactivity.

Aufbau Principle

The Aufbau Principle is like a guidebook for filling the orbitals with electrons in order of increasing energy level. It states that electrons occupy the lowest energy orbitals first before moving to higher energy levels. A helpful analogy is filling seats in a theater, starting from the front row and moving towards the back.

This principle follows a specific sequence depicted in a diagram known as an Aufbau chart, which organizes sublevels in order of their increasing energy. When applying the Aufbau Principle, remember that electrons won't enter a higher energy orbital until the lower ones are filled, much like patrons won't sit in the back row until the front is full.

Halogens

Halogens are a fascinating group of elements located in group 17 of the periodic table. They are one electron short of having a full valence shell, which makes them highly reactive. The family includes Fluorine, Chlorine, Bromine, Iodine, and Astatine.

Their eagerness to gain an electron and achieve a stable electron configuration underpins their notable reactivity. Not only are they reactive, but their reactions are often quite vigorous, particularly with alkali and alkaline earth metals. Because they are so close to completing their p sublevel, these elements form salts when they gain that missing electron, hence the name 'halogens,' meaning 'salt-former' in Greek.