Electron Configuration and Quantum Numbers

The ground state electron configuration of sulfur is

• 1s² 2s² 2p⁶ 3s² 3p⁴

• 1s² 2s² 2p⁴ 3s² 3p⁴

• 1s² 2s² 3s² 3p⁴

Answer explanation

The ground state electron configuration of sulfur (atomic number 16) is 1s² 2s² 2p⁶ 3s² 3p⁴, which accounts for all 16 electrons. The other options do not correctly represent the distribution of electrons.

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NGSS.HS-PS1-1

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Which principle states that no two electrons in an atom can have the same set of four quantum numbers?

• Hund's Rule.

• Pauli Exclusion Principle.

• Aufbau Principle.

• Heisenberg Uncertainty Principle.

Answer explanation

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers, ensuring that each electron is unique in its quantum state.

Which of the following quantum numbers is not possible for an electron in a 3d orbital?

• n = 3, l = 2, m = 2, s = +1/2

• n = 3, l = 2, m = 3, s = -1/2

• n = 3, l = 2, m = 1, s = +1/2

• n = 3, l = 2, m = 0, s = -1/2

Answer explanation

The quantum number m (magnetic quantum number) for a 3d orbital can range from -2 to +2. Therefore, m = 3 is not possible, making the choice 'n = 3, l = 2, m = 3, s = -1/2' the correct answer.

The image shows the partial electron configuration of manganese (Mn). Below there are two empty boxes. Correctly drag the final two answers in the correct order to finish its electron configuration.​

​ ​ (a)   ​ (b)  

• 4s²

• 3d⁵

• 1p⁶

• 2s³

• 3d⁹

• 2d⁹

Answer explanation

Manganese (Mn) has an atomic number of 25. Its electron configuration ends with 4s² and 3d⁵, filling the 4s subshell before the 3d subshell, which is consistent with the Aufbau principle.

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NGSS.HS-PS1-1

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Match the parts of the electron configuration to what it represents.

• element

• 1

• block

• 2

• period

• s

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NGSS.HS-PS1-1

Match the following

(a)   states that electrons fill the lowest energy orbitals first

• Heisenberg Uncertainty Principle

• Aufbau Principle

• Hund's Rule

• Mrs. Vollers

Match the following

• neon

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹

• oxygen

• 1s² 2s² 2p⁶ 3s² 3p²

• magnesium

• 1s² 2s² 2p⁶

• potassium

• 1s² 2s² 2p⁶ 3s²

• silicon

• 1s² 2s² 2p⁴

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NGSS.HS-PS1-1

What does the magnetic quantum number indicate?

• the energy level of the electron.

• the orientation of the orbital in space.

• the type of element in the periodic table.

• the size of the electron cloud.

Answer explanation

The magnetic quantum number specifies the orientation of an orbital in space, indicating how the orbital is aligned relative to the other orbitals. It does not determine energy level, element type, or size of the electron cloud.

Which of the following shapes best represents the d orbitals of a transition metal atom?

• a sphere.

• a cloverleaf.

• a cube.

• a pyramid.

Answer explanation

The d orbitals of transition metals are characterized by their cloverleaf shape, which consists of four lobes. This distinguishes them from s (spherical), p (dumbbell), and other shapes, making 'a cloverleaf' the correct choice.

What is the number of possible orientations for a "p" orbital around the nucleus?

• 1

• 2

• 3

• 4

Answer explanation

A 'p' orbital has three possible orientations in space, corresponding to the three axes (x, y, z). Therefore, the correct answer is 3.