Question

Indicate the total number of (a) \(p\) electrons in \(\mathrm{N}(Z=7)\) (b) \(s\) electrons in Si \((Z=14)\), and (c) \(3 d\) electrons in \(\mathrm{S}(Z=16)\)

Short answer

(a) 3, (b) 6, (c) 0

Step-by-step solution

Determine Electron Configuration for Nitrogen

Nitrogen (\(\mathrm{N}\) with \(Z = 7\)) has 7 electrons. Its electron configuration is 1s² 2s² 2p³. The \(p\) electrons are in the \(2p\) orbital, so there are 3 \(p\) electrons.

Count s Electrons in Silicon

Silicon (Si with \(Z = 14\)) has 14 electrons. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p². The \(s\) electrons are found in the 1s, 2s, and 3s orbitals, totaling 2 (1s) + 2 (2s) + 2 (3s) = 6 \(s\) electrons.

Determine the Number of 3d Electrons in Sulfur

Sulfur (\(\mathrm{S}\) with \(Z = 16\)) has 16 electrons. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁴. There are no electrons in the 3d orbital for sulfur, so the number of \(3d\) electrons is 0.

Key concepts

p Orbitals: The Home of P Electrons

The "p" orbitals are a crucial component of an atom's electron configuration and are quite unique in their properties. Imagine these orbitals like balloons or lobes stemming out in three dimensions. Each orbital can hold a maximum of two electrons.
In a given energy level, starting from the second level (n=2), three p orbitals can exist:

• Each individual p orbital is labeled as p_x, p_y, or p_z.
• Together, they can hold a maximum of 6 electrons, 2 in each orbital (p_x, p_y, and p_z).

For example, nitrogen (N), with 7 electrons, has an electron configuration of 1s² 2s² 2p³. Here, the 3 electrons in the 2p orbital mean it is partially filled, making nitrogen especially reactive. Understanding p orbitals helps us follow how atoms form bonds, as these orbitals are often involved in the process.

s Orbitals: The Simplest Orbitals

The "s" orbitals are simpler in shape compared to p orbitals and exactly spherical, like tiny bubbles or balls surrounding the nucleus of an atom. In each energy level, one s orbital exists.

• An s orbital can hold a maximum of 2 electrons.
• The s orbitals appear in all energy levels of the atom, starting from the first level.

Take silicon (Si), with atomic number 14. Silicon's electron configuration is 1s² 2s² 2p⁶ 3s² 3p². If you count the electrons in the s orbitals of this configuration: 2 from 1s, 2 from 2s, and another 2 from 3s, you get a total of 6 s electrons.
Understanding s orbitals is fundamental as they are the first orbitals filled during electron configuration and contribute significantly to the chemical properties of elements.

Understanding Electron Count in Electron Configuration

Electron configuration is key to understanding the way an element behaves chemically. It tells us how electrons are distributed across the different orbitals of an atom. These distributions explain why some elements tend to bond in certain ways, while others do not.
The electron count involves determining the number of electrons in each type of orbital:

• s orbitals: Always start from 1s and go to the maximum energy level available for the element.
• p orbitals: Begin filling from n=2, with a sequence you have 2p, 3p, and so on.
• d orbitals: Start appearing from the third energy level (3d), adding more complexity.

Sulfur (S), for instance, has 16 electrons as shown by its electron configuration 1s² 2s² 2p⁶ 3s² 3p⁴. In this sequence, there are no electrons in 3d orbitals, but instead, a thoughtful arrangement of s and p ensures sulfur's status as a reactive nonmetal.
Counting electrons aids in predicting both the chemical and physical properties of the elements, thereby playing a critical role in understanding chemistry.