Hund's Rule and Electron Configuration

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Questions and Answers

What is the significance of the concept of quantization in Bohr's atomic model?

It means that the energy of the atom can only take on specific discrete values, not a continuous range of values.

What happens to the electron when it moves from a higher energy level to a lower energy level in the Bohr model?

Light is emitted.

What is the relationship between the energy level and the distance of the electron's orbit from the nucleus in the Bohr model?

The higher the energy level, the farther the orbit is from the nucleus.

What is the significance of the principal quantum number (n) in the Bohr model?

It determines the energy level of the electron. Signup and view all the answers

What is the state of the atom when the electron is in the first orbit?

The ground state, or the lowest energy state. Signup and view all the answers

What is the significance of the concept of stationary states in the Bohr model?

It refers to the specific energy levels that the electron can occupy. Signup and view all the answers

How does the Bohr model explain the structure of the atom when it undergoes energy transitions?

The energy of the atom changes when the electron moves from one energy level to another. Signup and view all the answers

What is the major idea behind Bohr's atomic model?

That the energy of the atom is quantized, and related to the electron's position in the atom. Signup and view all the answers

What is the reason for the electrical neutrality of an atom?

The number of protons is equal to the number of electrons Signup and view all the answers

Who proposed the model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces?

Thomson Signup and view all the answers

What is the main principle of Hund's rule in the arrangement of electrons in subshells?

The most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins. Signup and view all the answers

What is the characteristic of the nucleus in Rutherford's model?

A dense central core within an atom with positive charge Signup and view all the answers

What is the dual nature of electron according to De Broglie's postulate and Heisenberg's uncertainty principle?

Electron is both a particle and a wave, and its energy is quantized, but it's not possible to know its position and momentum with unlimited accuracy Signup and view all the answers

What is the correct set of quantum numbers for the third electron of the F atom?

n = 2, l = 0, ml = 0, ms = +½ Signup and view all the answers

What is the result of an atom losing or gaining electrons in a chemical reaction?

The atom becomes an ion Signup and view all the answers

What is the difference between a partial orbital diagram and a condensed electron configuration?

A partial orbital diagram shows only the highest energy sublevels being filled, while a condensed electron configuration has the element symbol of the previous noble gas in square brackets. Signup and view all the answers

What is the significance of the number of protons in an atom?

The number of protons is equal to the number of electrons, making the atom electrically neutral Signup and view all the answers

What is the purpose of using the element symbol of the previous noble gas in square brackets in a condensed electron configuration?

It represents the underlying electron configuration of the noble gas. Signup and view all the answers

Why is the arrangement of electrons in (c) more acceptable than (a) and (b) according to Hund's rule?

Because it has the greatest number of parallel spins. Signup and view all the answers

What is the significance of the ms value in the set of quantum numbers for an electron?

It represents the spin of the electron, which can be either +½ or -½. Signup and view all the answers

What is the purpose of using partial orbital diagrams?

To show only the highest energy sublevels being filled. Signup and view all the answers

Why is the electron configuration of Al written as [Ne]3s23p1 in condensed form?

Because it has the element symbol of the previous noble gas (Ne) in square brackets. Signup and view all the answers

What is the purpose of the spin quantum number (m) in describing electrons in atoms?

to describe the spin of a specific electron and complete the description of electrons in atoms Signup and view all the answers

What happens to the energy and size of an orbital as the principal quantum number (n) increases?

The energy and size of the orbital increase as the principal quantum number (n) increases Signup and view all the answers

What is the relationship between the principal quantum number (n) and the angular momentum quantum number (l)?

For a given value of n, l = 0, 1, 2, 3, … n-1 Signup and view all the answers

How many orbital diagrams are associated with l = 2 (d orbitals)?

5 Signup and view all the answers

What is the range of values for the magnetic quantum number (ml) for a given value of l?

integers from −l to +l including zero Signup and view all the answers

What is the significance of the principal energy level (or shell) in the electron configuration of an atom?

Orbitals with the same value of n are in the same principal energy level (or shell) Signup and view all the answers

What is the total number of orbitals in an electron shell?

9 Signup and view all the answers

What are the four quantum numbers for an electron in a 3p orbital?

n = 3, l = 1, m = -1, 0, or 1, ms = +½ or -½ Signup and view all the answers

What is the Spin Quantum Number, ms, and what are its possible values?

The Spin Quantum Number, ms, is the fourth quantum number that describes the spin orientation of an electron, and its possible values are +½ or -½. Signup and view all the answers

How are electrons represented in an orbital diagram?

Electrons are represented by half-arrows in an orbital diagram, with a half-arrow pointing up representing an electron with spin up and a half-arrow pointing down representing an electron with spin down. Signup and view all the answers

What is the maximum number of electrons that can reside in the principal level for which n = 3?

18 Signup and view all the answers

Write the four quantum numbers for each of the eight electrons in the ground state of an oxygen atom.

See below. Note: This requires a separate answer for each of the 8 electrons, which depends on the specific electron configuration of oxygen. Signup and view all the answers

Study Notes

Atomic Structure

An atom is electrically neutral because the number of protons are equal to the number of electrons.
Atoms do not lose or gain protons in any chemical reaction, but they do lose or gain electrons to become ions.

Nuclear Atomic Model

Thomson's model: proposed a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces.
Rutherford's model: atoms have a positive charge concentrated in the nucleus (dense central core within an atom).
Dual nature of electrons: electron energy is quantized, and electron is both particle and wave.
De Broglie's postulate: electron has wave-like properties.
Heisenberg's uncertainty principle: not possible to know the unlimited accuracy both the position and momentum of an electron.

Bohr's Atomic Model

Bohr's model: energy of the atom is quantized, and the amount of energy in the atom is related to the electron's position in the atom.
Postulates:
- The single electron in H atom moves around the nucleus in orbits or energy levels.
- The H atom has only certain energy levels, which are called stationary states.
- Each state is associated with a fixed circular orbit of the electron around the nucleus.
- The higher the energy level, the farther the orbit is from the nucleus.
- When the H electron is in the first orbit, the atom is in its lowest energy state, called the ground state.

Quantum Numbers

Principal quantum number (n): describes the energy level of an electron.
- n can be any integer ≥ 1.
- The larger the value of n, the more energy the orbital has.
- The larger the value of n, the larger the orbital.
Angular momentum quantum number (l): describes the shape of the orbital.
- l = 0, 1, 2, 3, … n-1.
- Shape of the orbital changes with l.
Magnetic quantum number (ml): describes the orientation of the orbital.
- ml = -l, …., 0, ….
- The total number of orbitals is 1 + 3 + 5 = 9.
Spin quantum number (ms): describes the spin of an electron.
- ms = +½ or −½.
- Spin up or spin down.

Electron Configurations and Orbital Diagrams

Electron spin: a fundamental property of all electrons.
Orbital diagrams: use a square to represent each orbital and a half-arrow to represent each electron in the orbital.
By convention, a half-arrow pointing up is used to represent an electron in an orbital with spin up.
Spins must cancel in an orbital with 2 electrons (paired e-).

Electronic Configurations

Partial orbital diagrams: show only the highest energy sublevels being filled.
Condensed electron configurations: have the element symbol of the previous noble gas in square brackets.
Hund's rule: the most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins.

Checkpoints

Checkpoint 3: write the four quantum numbers for an electron in a 3p orbital.
Checkpoint 4: the maximum number of electrons that can reside in the orbitals is 2 × 9 = 18.
Checkpoint 5: write the four quantum numbers for each of the eight electrons in the ground state of an oxygen atom.

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Description

This quiz is about Hund's rule and electron configuration in atoms, including parallel spins and subshell arrangements.