Problem 23 - Chemistry Matter and Change

Question

When a sulfur atom reacts with other atoms, electrons in orbitals related to the atom's third energy level are involved. How many such electrons does a sulfur atom have?

Step-by-Step Solution

Answer

Sulfur has 6 electrons in its third energy level.

Step 1: Identify the atomic number of sulfur

Sulfur is an element with the atomic number 16 on the periodic table.

Step 2: Write the electron configuration

The electron configuration helps to determine how the electrons are arranged in the energy levels. For sulfur, the ground-state electron configuration is: \[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^4 \]

Step 3: Determine the electron occupancy of the third energy level

The third energy level for sulfur is comprised of the 3s and 3p orbitals. According to the electron configuration, the 3s orbital has \(2\) electrons and the 3p orbital possesses \(4\) electrons.

Step 4: Calculate the total number of electrons in the third energy level

Sum the electrons in both the 3s and 3p orbitals to find the total in the third energy level: \(2 \text{(from 3s)} + 4 \text{(from 3p)} = 6\)

Key Concepts

Atomic Number

The atomic number is a fundamental characteristic of every element on the periodic table. It defines the identity of an element as it corresponds to the number of protons found in the nucleus of an atom of that element. For sulfur, the atomic number is 16.

This number not only signifies the total number of protons but also the number of electrons in a neutral atom. The number of electrons is crucial because it influences the chemical behavior and bonding capabilities of the element.

For example, in the case of sulfur, with an atomic number of 16, we know it has 16 electrons that will fill different energy levels and orbitals around the nucleus. Understanding this allows us to determine how sulfur interacts with other elements and forms compounds.

Electron Configuration

The electron configuration of an element describes the distribution of electrons among various orbitals in an atom. It provides insight into how electrons are organized into different energy levels to achieve a stable configuration. For sulfur, the electron configuration is \[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^4 \].

This notation lists electrons from the lowest to highest energy level, allocating them into orbitals in a designated order.

• 1s, 2s, and 2p: These orbitals hold 10 electrons in total, completing the first two energy levels.
• 3s and 3p: There are 6 electrons here, indicating partial occupancy of the third energy level specific to sulfur.

Through electron configuration, chemists can predict chemical properties such as valency and reactivity.

Energy Levels

Energy levels, sometimes referred to as electron shells, are layers around an atomic nucleus where electrons are found. These are arranged according to increasing energy, starting from the nucleus outward. Each energy level can hold a specific number of electrons before they proceed to the next level.

For sulfur, its electrons occupy the first three energy levels. Each level can be divided into subshells or orbitals, denoted by the letters s, p, d, and f. In sulfur's case:

• First energy level: Contains 2 electrons in the 1s orbital.
• Second energy level: Holds 8 electrons across 2s and 2p orbitals.
• Third energy level: Contains 6 electrons distributed in the 3s and 3p orbitals.

These levels represent increasing energy, and electrons will fill them sequentially to minimize energy and achieve stability.

Orbitals

Orbitals are regions within an atom where electrons are likely to be found. They are not fixed paths but rather probabilistic zones. Each type of orbital (s, p, d, f) has a unique shape and capacity for holding electrons.

In the case of sulfur:

• s orbitals: Spherical in shape, can hold up to 2 electrons. In sulfur, the 3s subshell holds 2 electrons.
• p orbitals: Dumbbell-shaped, each set can accommodate up to 6 electrons (2 per orbital). In sulfur, the 3p subshell holds 4 electrons, leaving 2 spots potentially available for bonding.

These orbitals determine the chemical properties and reactivity of sulfur. Knowing how electrons fill these orbitals helps understand how sulfur bonds with other elements, forming compounds such as sulfides or sulfates.