Question

Write the electron arrangement for each of the following clements: (Example: sodium \(2,8,1\) ) 3\. carbon \(\mathbf{b}\). argon c. potassium d. silicon e. helium f. nitrogen

Short answer

Carbon: 2,4; Argon: 2,8,8; Potassium: 2,8,8,1; Silicon: 2,8,4; Helium: 2; Nitrogen: 2,5.

Step-by-step solution

Understand Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. Use the order of orbitals: 1s, 2s, 2p, 3s, 3p, 4s, etc.

Carbon

Carbon has 6 electrons. Arrange them in the orbitals: 1s² 2s² 2p². This corresponds to the electron arrangement: 2, 4.

Argon

Argon has 18 electrons. Arrange them in the orbitals: 1s² 2s² 2p⁶ 3s² 3p⁶. This corresponds to the electron arrangement: 2, 8, 8.

Potassium

Potassium has 19 electrons. Arrange them in the orbitals: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹. This corresponds to the electron arrangement: 2, 8, 8, 1.

Silicon

Silicon has 14 electrons. Arrange them in the orbitals: 1s² 2s² 2p⁶ 3s² 3p². This corresponds to the electron arrangement: 2, 8, 4.

Helium

Helium has 2 electrons. Arrange them in the orbitals: 1s². This corresponds to the electron arrangement: 2.

Nitrogen

Nitrogen has 7 electrons. Arrange them in the orbitals: 1s² 2s² 2p³. This corresponds to the electron arrangement: 2, 5.

Key concepts

electron arrangement

Electron arrangement (or electron configuration) is a way of depicting how electrons are distributed in an atom's orbital. Each atom has a unique arrangement based on its number of electrons. To determine the configuration, we use specific rules and order of orbitals. Each orbital can hold a specific maximum number of electrons: the s orbital holds 2, p holds 6, d holds 10, and f holds 14. So, the electron arrangement can be shown simply by counting the electrons and arranging them in the correct order of the orbitals.

atomic orbitals

Atomic orbitals are regions in an atom where the probability of finding an electron is highest. They come in different shapes (s, p, d, f) and sizes. The s orbitals are spherical, p orbitals are dumbbell-shaped, and d and f orbitals have even more complex shapes.

These orbitals are arranged around the nucleus and designated by quantum numbers. For example:

• 1s: n=1, l=0
• 2p: n=2, l=1
• 3d: n=3, l=2

The principal quantum number (n) tells us about the energy level, and the angular momentum quantum number (l) indicates the shape of the orbital. Higher values of n mean higher energy levels and more complex shapes.

electron distribution

Electron distribution across atomic orbitals follows a specific pattern. It's governed by three fundamental principles: Aufbau Principle, Pauli Exclusion Principle, and Hund's Rule:

• Aufbau Principle: Electrons fill the lowest energy orbitals first. For example, 1s is filled before 2s.
• Pauli Exclusion Principle: Each orbital can hold a maximum of two electrons with opposite spins.
• Hund's Rule: Electrons spread out across orbitals of the same energy before pairing up. In a p orbital, for example, three electrons would occupy three different p orbitals before any two electrons share the same p orbital.

These rules ensure the electrons are distributed as evenly and stably as possible within an atom.

orbital filling order

The order in which atomic orbitals are filled is crucial for understanding electronic structure. We typically use the following order based on increasing energy levels:

• 1s
• 2s
• 2p
• 3s
• 3p
• 4s
• 3d
• 4p
• 5s
• 4d
• 5p
• 6s
• 4f
• 5d
• 6p
• 7s
• 5f
• 6d
• 7p

This 'filling order' follows the Aufbau principle, where electrons occupy the lowest available energy levels first. For example, in potassium (atomic number 19), the filling order proceeds as: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹. This orderly filling explains the specific electron configurations of elements.