Question

Write the expected electron configurations for each of the following atoms: Sc, Fe, P, Cs, Eu, Pt, Xe, Br.

Short answer

The electron configurations for the given elements are: Sc: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^1\) Fe: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6\) P: \(1s^2 2s^2 2p^6 3s^2 3p^3\) Cs: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^1\) Eu: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^7\) Pt: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^9\) Xe: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6\) Br: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5\)

Step-by-step solution

1. Sc (Scandium)

Scandium has 21 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^1\]

2. Fe (Iron)

Iron has 26 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6\]

3. P (Phosphorus)

Phosphorus has 15 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^3\]

4. Cs (Cesium)

Cesium has 55 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^1\]

5. Eu (Europium)

Europium has 63 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^7\]

6. Pt (Platinum)

Platinum has 78 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^9\]

7. Xe (Xenon)

Xenon has 54 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6\]

8. Br (Bromine)

Bromine has 35 electrons. Its electron configuration is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5\] These are the expected electron configurations for each of the given elements.

Key concepts

Atomic Structure

Understanding atomic structure is fundamental for grasping concepts in chemistry, such as electron configurations. An atom consists of a nucleus containing protons and neutrons, surrounded by electrons that occupy regions of space known as electron shells or energy levels.

These electrons are arranged in specific patterns that correspond to different energy levels, and they fill up from the lowest energy level to the highest according to the Aufbau principle. The number of protons in the nucleus determines the element's identity and its position in the periodic table, while the arrangement of electrons defines the atom's reactivity and bonding characteristics.

The Quantum Model

In the quantum mechanical model of the atom, electrons reside in orbitals - specific regions within the energy levels with high probabilities of finding an electron. Each orbital can hold a maximum of two electrons with opposite spins.

These details play an integral role in the visualization of electron configurations, allowing us to predict how atoms will interact in chemical reactions.

Periodic Table

The periodic table is a tabular display of all known chemical elements, organized by increasing atomic number. It is a powerful tool for predicting the properties of elements and their compounds. The table is structured into rows called periods and columns known as groups or families.

Elements within the same group share similar electron configurations in their valence shells, which is the outermost electron shell, leading to resemblances in chemical behavior. As you move across a period from left to right, the atomic number increases, and one electron is added to the valence shell.

Trends in the Periodic Table

There are recurring trends in the periodic table, such as ionization energy, atomic radius, and electronegativity, which can be understood by considering atomic structure and electron configurations. These patterns are valuable for chemists who use them to explain and predict the outcome of chemical reactions.

Electron Configuration Notation

Electron configuration notation is a method used to describe the distribution of electrons among the orbitals of an atom. It is a written representation showing the number of electrons within each energy level and sublevel according to the known order of orbital filling.

The notation consists of a sequence of numbers and letters, where the number denotes the energy level, the letter indicates the type of orbital (s, p, d, f), and the superscript gives the number of electrons in that orbital. For example, 1s² means that there are two electrons in the 1s orbital.

Importance of Electron Configuration

Accurate electron configuration is crucial for predicting an element’s chemical properties and behavior. It affects the atom's magnetic properties, its ability to bond with other atoms, and its color when involved in compounds. Proper notation and understanding of this concept can significantly improve a student's ability to engage with chemistry, from simple reactions to complex mechanisms involving electron transfer.