Question

Which of the following elements has least number of electrons in its \(\mathrm{M}\) shell? (a) \(\mathrm{Mn}\) (b) \(\mathrm{Ni}\) (c) \(\mathrm{K}\) (d) \(\mathrm{Sc}\)

Short answer

Potassium (K) has the least number of electrons in its M shell.

Step-by-step solution

Understanding Electron Configuration

The electron configuration of an element tells us how electrons are distributed in shells and subshells. The M shell corresponds to the third shell (n=3) which can hold a maximum of 18 electrons.

Electron Configuration Definitions

Determine the electron configurations for each element based on their atomic numbers: (a) Manganese (Mn): Atomic number 25 (b) Nickel (Ni): Atomic number 28 (c) Potassium (K): Atomic number 19 (d) Scandium (Sc): Atomic number 21.

Electron Configuration for Potassium

Potassium (K), with atomic number 19, has the electron configuration: \[ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 \]The M shell (3rd shell) contains electrons from the 3s and 3p subshells, totaling 8 electrons.

Electron Configuration for Manganese

Manganese (Mn), with atomic number 25, has the electron configuration: \[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^2 \]The M shell includes electrons from the 3s, 3p, and 3d subshells, totaling 13 electrons.

Electron Configuration for Nickel

Nickel (Ni), with atomic number 28, has the electron configuration: \[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2 \]The M shell includes electrons from the 3s, 3p, and 3d subshells, totaling 18 electrons.

Electron Configuration for Scandium

Scandium (Sc), with atomic number 21, has the electron configuration:\[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^1 4s^2 \]The M shell includes electrons from the 3s, 3p, and 3d subshells, totaling 11 electrons.

Comparison of Electrons in the M Shell

We have determined the number of electrons in the M shell for each element: - Mn: 13 electrons - Ni: 18 electrons - K: 8 electrons - Sc: 11 electrons Potassium (K) has the least number of electrons in its M shell with 8 electrons.

Key concepts

Atomic Structure

The atomic structure is like a map detailing how atoms are built. Every atom is made up of three primary particles: protons, neutrons, and electrons. These particles are organized in a specific way within the atom. At the core is the nucleus, which houses the protons and neutrons, while electrons swirl around the nucleus in different regions known as electron shells or levels.

Atomic Nucleus

• Protons: This particle carries a positive charge (+1), and the number of protons in an atom determines the atomic number and defines the element.
• Neutrons: These particles have no charge and add to the mass of the atom, contributing to isotopes.

Electron Shells

• Electrons: These particles are negatively charged (-1) and are found in regions outside the nucleus.
• Electrons are organized in shells based on energy levels, and each shell can hold a specific number of electrons.

Electron Shells

Electron shells are crucial for understanding how electrons arrange themselves around the nucleus of an atom. Each shell represents an energy level, and electrons fill these shells starting from the lowest energy level to the highest. The shells are labeled as K, L, M, N, and so on, beyond which there are multiple subshells.

Understanding Electron Configuration

• The electron configuration of an element shows how electrons are distributed in these different shells and subshells.
• The M shell corresponds to the third energy level, which can contain up to 18 electrons spread across its 3s, 3p, and 3d subshells.

The Structure of Subshells

• The 3s and 3p subshells together can hold up to 8 electrons (2 in 3s and 6 in 3p).
• The 3d subshell, however, can hold an additional 10 electrons, which allows the M shell to house a total of 18 electrons.

Chemical Elements

Chemical elements are the building blocks of everything we see around us. Each element is defined by its unique atomic number, which is the count of protons in its nucleus. On the periodic table, elements are organized by their atomic numbers and exhibit a variety of chemical and physical properties.

Basic Characteristics

• Elements with similar properties are placed in columns known as groups.
• Their atomic numbers, electron configurations, and recurring chemical properties organize elements into a systematic layout.

Relationship with Electron Configuration

• The electron configuration of an element dictates how it interacts with other elements, influencing chemical reactions and bonding.
• Knowing an element's electron configuration can help predict its chemical behavior and position in the periodic table.