Question

Write the electron configurations for \(P\) and \(C l\) using both spdf notation and orbital box diagrams. Describe the relationship between each atom's electron configuration and its position in the periodic table.

Short answer

Phosphorus has configuration \([Ne]3s^2 3p^3\), chlorine \([Ne]3s^2 3p^5\). Their positions in the periodic table reflect their valence electrons.

Step-by-step solution

Identify Atomic Numbers

Start by identifying the atomic numbers of phosphorus (\(P\)) and chlorine (\(Cl\)). Phosphorus has an atomic number of 15, while chlorine has an atomic number of 17. This means phosphorus has 15 electrons, and chlorine has 17 electrons.

Write Electron Configuration for Phosphorus

To write the electron configuration of phosphorus in spdf notation, distribute the 15 electrons across orbitals following the order of increasing energy levels: \(1s^2\), \(2s^2\), \(2p^6\), \(3s^2\), \(3p^3\). Phosphorus has the configuration \([Ne]3s^2 3p^3\).

Orbital Box Diagram for Phosphorus

In an orbital box diagram, each orbital is represented by a box, and electrons are shown as arrows. Fill the orbitals for phosphorus as follows: 1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑ ↑ ↑ This diagram shows one electron in each of the 3p orbitals.

Write Electron Configuration for Chlorine

For chlorine, distribute the 17 electrons: \(1s^2\), \(2s^2\), \(2p^6\), \(3s^2\), \(3p^5\). Chlorine has the configuration \([Ne]3s^2 3p^5\). This configuration shows that chlorine is one electron short of having a filled valence shell.

Orbital Box Diagram for Chlorine

Fill the orbitals in chlorine's diagram as follows: 1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑ This illustrates that the 3p subshell has 5 electrons, indicating its group position in the periodic table.

Relate to Periodic Table Position

Phosphorus is in group 15 and period 3, characterized by having three p electrons in the outer shell, resulting in 5 total valence electrons. Chlorine is in group 17 and period 3, with five p electrons and 7 total valence electrons. This is consistent with their electron configurations, reflecting their reactive nature and typical ionic charges (-3 for phosphorus and -1 for chlorine).

Key concepts

Orbital Box Diagrams

Orbital box diagrams are visual representations used to depict electron configurations in atoms. Each box represents an atomic orbital, and these boxes are filled with arrows that symbolize electrons. Each arrow has a direction, either up or down, indicating the electron's spin. According to the principle of electron configuration, known as the Pauli Exclusion Principle, no two electrons within an atom can have the same set of four quantum numbers—this accounts for why arrows in the same box must be opposite.

• Each box corresponds to one orbital.
• Electrons (arrows) fill orbitals starting from the lowest energy.
• Arrows represent electrons with different spins.

For example, in phosphorus, which has 15 electrons, the orbital box diagram is filled as follows: - **1s:** Two electrons, both in the same box, but with opposite spins. - **2s:** Same as 1s. - **2p:** Three boxes for p orbitals, each filled with two electrons until the orbitals are full. - **3s:** Two electrons. - **3p:** Three boxes again, but note phosphorus fills two p orbitals with a single electron each, and the third with one more to achieve its unique configuration.
This visual aid helps in understanding how electrons are distributed and how they pair, ultimately aiding in the prediction of physical and chemical properties.

Periodic Table

The periodic table is a powerful tool in chemistry that organizes elements according to their atomic number, electron configurations, and recurring chemical properties. The layout of the periodic table provides insights into the behavior and characteristics of elements.

• Groups: Vertical columns on the table, indicating the number of valence electrons.
• Periods: Horizontal rows, signifying the number of electron shells.

Taking phosphorus and chlorine as examples, we can relate their positions on the periodic table to their electron configurations: - **Phosphorus (Group 15, Period 3):** Its position indicates it has three filled energy levels, with five electrons in the outermost shell. - **Chlorine (Group 17, Period 3):** Chlorine has seven valence electrons as indicated by its group number, showing it's one electron short of a stable noble gas configuration.
The periodic table arrangement not only predicts properties like reactivity and ionization energy but also shows how these elements will likely interact with others. Understanding the periodic table’s structure can clarify why phosphorus typically forms a i.e., -3 charge while chlorine often results in a -1 charge when forming ionic compounds.

spdf Notation

The spdf notation is a shorthand method to portray an element's electron configuration. It is based on the distribution of electrons within the energy subshells: - **s** for sharp- **p** for principal- **d** for diffuse- **f** for fundamental
Each subshell has a specific number of orbitals: - An s subshell has 1 orbital (up to 2 electrons).- A p subshell has 3 orbitals (up to 6 electrons).- A d subshell has 5 orbitals (up to 10 electrons).- An f subshell has 7 orbitals (up to 14 electrons).
For example, phosphorus () shows a notation ending in \(3s^2 3p^3\), which signifies the electrons in the third energy level occupy s and p subshells with two and three electrons respectively.
Understanding spdf notation enables chemists to predict how atoms will bond and the types of chemical reactions they might participate in. Additionally, it also relates to the element's position on the periodic table, revealing insights into properties such as magnetism, bonding, and reactivity.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining the chemical behavior of an element. These electrons partake in bonding, and their configuration heavily influences an element’s chemical stability and reactivity.

• Significance in Bonding: They are the electrons involved in forming bonds with other atoms.
• Determination: The number of valence electrons is often tied to an element's group number in the periodic table.

For instance, phosphorus has 5 valence electrons, correlating with its position in Group 15. This configuration explains why phosphorus can typically form three covalent bonds. On the other hand, chlorine, with its 7 valence electrons, is eager to gain one more electron to attain a full octet, explaining its typical -1 ionic charge.
Understanding valence electrons not only helps to predict the types of bonds an element might form but also assists in determining molecular structure and polarity. The pursuit of stable electron configurations, often a complete valence shell, drives many of the predictable patterns seen in chemical reactions. This concept is foundational in explaining why elements behave the way they do in nature and in various reactions.