Chemistry Chapter 7: Atomic Structure

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Questions and Answers

What are the three characteristics of electromagnetic radiation?

Wavelength, amplitude, mass

Frequency, speed, temperature

Wavelength, frequency, speed (correct)

Amplitude, wave number, density

What is the value of the speed of light (c)?

3.0 × 10^8 m/s

2.9979 × 10^8 m/s (correct)

1.5 × 10^8 m/s

6.626 × 10^8 m/s

Which of the following describes the term wavelength (λ)?

The total number of waves passing a point per second

The speed at which waves travel through a medium

The energy associated with a single waveform

The distance between two consecutive peaks or troughs in a wave (correct)

What is meant by energy being quantized?

Energy can only be absorbed or emitted in whole number multiples. Signup and view all the answers

What is Planck's constant (h)?

6.626 × 10^-34 J·s Signup and view all the answers

Which of the following statements correctly describes the dual nature of light?

Light exhibits properties of both waves and particles. Signup and view all the answers

What does the term photon refer to?

A particle representing a quantum of light Signup and view all the answers

What is the relationship between energy (E) and mass (m) as described by the formula E = mc^2?

Energy and mass are equivalent and can be converted into each other. Signup and view all the answers

What distinguishes a line spectrum from a continuous spectrum?

A line spectrum consists of discrete wavelengths. Signup and view all the answers

In the context of hydrogen's emission spectrum, what does 'quantized energy' imply?

Electrons can only exist in specific energy levels. Signup and view all the answers

What characterizes the ground state of an electron in a hydrogen atom?

It corresponds to the lowest energy level (n = 1). Signup and view all the answers

Which of the following best describes the relationship between electronic transitions and the Bohr model?

Electrons occupy circular orbits at certain energy levels. Signup and view all the answers

What does the formula for energy change (ΔE) indicate in the Bohr model for a hydrogen atom?

The formula allows calculation of the energy of emitted photons. Signup and view all the answers

What is true about the energy levels in the hydrogen atom according to the Bohr model?

Only specific energy levels are permitted. Signup and view all the answers

How does the hydrogen emission spectrum demonstrate the idea of quantized energy levels?

It produces distinct lines corresponding to specific energies. Signup and view all the answers

Which of the following statements is true regarding electron transitions in the Bohr model?

Energy levels determine the wavelengths of emitted light. Signup and view all the answers

Which of the following describes Mendeleev's contribution to the periodic table?

He emphasized the predictive capabilities of the periodic table. Signup and view all the answers

What is the electron configuration of an oxygen atom?

1s22s22p4 Signup and view all the answers

According to Hund's Rule, how should electrons be distributed in degenerate orbitals?

Each orbital must hold one electron before any hold two. Signup and view all the answers

Which statement about valence electrons is correct?

The number of valence electrons determines an element's chemical properties. Signup and view all the answers

What do the radial probability distributions of the 2s and 2p orbitals illustrate?

The electron density as a function of distance from the nucleus. Signup and view all the answers

What does the Aufbau principle state regarding electron configuration?

Electrons occupy the lowest available energy orbitals first. Signup and view all the answers

How does the arrangement of elements in the periodic table affect their chemical properties?

Similar properties arise from having similar valence electron configurations. Signup and view all the answers

Which characteristic is NOT true about degenerate orbitals?

They must be filled before electrons can occupy higher energy orbitals. Signup and view all the answers

What does the Bohr model of the hydrogen atom postulate about electron orbits?

Only certain allowed circular orbits exist for the electron. Signup and view all the answers

As an electron becomes more tightly bound to the nucleus, what happens to its energy?

Its energy becomes more negative. Signup and view all the answers

Which transition of an electron in the hydrogen atom results in the emission of blue light?

n = 5 to n = 2 Signup and view all the answers

What is the primary limitation of the Bohr model?

It only works for hydrogen atoms. Signup and view all the answers

Which quantum number determines the shape of atomic orbitals?

Angular momentum quantum number (l) Signup and view all the answers

What does the 1s orbital represent in the quantum mechanical model?

A three-dimensional density map enclosing 90% of the electron's probability. Signup and view all the answers

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

It dictates the size and energy of the orbital. Signup and view all the answers

Which of the following describes a characteristic of the quantum mechanical model of the atom?

It incorporates wave functions to describe electron behavior. Signup and view all the answers

How many allowed subshells are there for the principal quantum level n = 3?

3 Signup and view all the answers

What are the designations for the allowed subshells corresponding to l = 0, 1, and 2 at n = 3?

3s, 3p, 3d Signup and view all the answers

What is the range of magnetic quantum numbers (ml) for l = 2?

-2, -1, 0, 1, 2 Signup and view all the answers

What is the maximum number of orbitals that can exist for a subshell with l = 2?

5 Signup and view all the answers

Which statement about electron spin is correct?

Electron spin quantum numbers can only be +½ or -½. Signup and view all the answers

What does the Pauli exclusion principle state regarding electrons in an atom?

No two electrons can have the same set of four quantum numbers. Signup and view all the answers

Which of the following describes the penetration effect in polyelectronic atoms?

An electron in a 2s orbital is attracted to the nucleus more than that in 2p. Signup and view all the answers

What is the electron configuration for sulfur (S)?

1s22s22p63s23p4 Signup and view all the answers

When electrons are placed in a particular quantum level, what is the preferred order for orbitals?

s, p, d, f Signup and view all the answers

Which element has the electron configuration of [Xe]6s2?

Barium (Ba) Signup and view all the answers

What trend is observed in first ionization energy as you move across a period from left to right?

It increases overall. Signup and view all the answers

Why does ionization energy generally decrease as you move down a group?

Electrons are farther from the nucleus. Signup and view all the answers

Which ionization energy requires the most energy to remove an electron?

Ionic bond of chlorine (Cl) Signup and view all the answers

What does the electron configuration [Xe]6s24f7 represent?

Europium (Eu) Signup and view all the answers

Which of the following statements about ionization energy is true?

Removing an electron always requires energy. Signup and view all the answers

Which of these pairs exhibit an exception in the ionization energy trend across periods?

Be and B Signup and view all the answers

Study Notes

Chapter 7: Atomic Structure and Periodicity

This chapter covers atomic structure and how elements are arranged in the periodic table. It focuses on the properties of these elements, and the reasoning behind the organization of the periodic table.
The study of electromagnetic radiation and its properties is presented as a fundamental component.

Section 7.1: Electromagnetic Radiation

Electromagnetic radiation are ways energy travels through space.
Characteristics include: wavelength, frequency, and speed.
Wavelength (λ) is the distance between two consecutive peaks or troughs of a wave.
Frequency (ν) is the number of waves passing a given point per second, measured in Hertz (Hz).
Speed (c) is the speed of light, approximately 2.9979 × 10⁸ m/s.
The relationship between these three variables is: c = λν

Section 7.2: The Nature of Matter

Energy is quantized, meaning energy can only be gained or lost in whole-number multiples of specific packets.
Electromagnetic radiation behaves as a stream of "particles" called photons.
The energy of a photon is given by Ephoton = hv = hc/λ, with h being Planck's constant (6.626 × 10⁻³⁴ J•s)
Energy has mass according to E = mc².
Light and all matter exhibit both wave and particle properties (wave-particle duality).
Light has a dual nature.

Section 7.3: The Atomic Spectrum of Hydrogen

Continuous spectrum: white light passed through a prism displays all wavelengths of visible light.
Line spectrum: each line corresponds to a specific discrete wavelength. This is characteristic of atoms as they emit light at specific wavelengths.
Hydrogen emission spectrum: a line spectrum unique to the hydrogen atom.
The spectrum's distinct lines reveal discrete energy levels within the hydrogen atom, implying that electron energies are quantized.

Section 7.4: The Bohr Model

Electrons in a hydrogen atom are restricted to specific circular orbits around the nucleus.
Bohr's model aligns with the quantized energy levels observed in the hydrogen emission spectrum.
Ground state: The lowest energy level (n = 1) is the most stable state.
A transition to a different orbital will occur only if a certain amount of energy is absorbed (if going to higher energy level) or emitted (if going to a lower energy level).
The change in energy (ΔE) associated with a transition between different energy levels, is given by : ∆Ε = - 2.178 ×10^⁻¹⁸ J * ( 1/n²final - 1/n²initial).

Section 7.5: The Quantum Mechanical Model of the Atom

It's impossible to precisely specify the location of an electron, but one can describe the area around the nucleus where it's most likely to be found. The most likely location is described with orbital regions.
Orbitals are described as a three-dimensional electron density map.
A radius of a sphere is calculated that contains 90% of the total probability of finding an electron, with a specific radial probability distribution.

Section 7.6: Quantum Numbers

Several quantum numbers govern the properties and arrangements of electrons in an atom.
Principal quantum number (n): Describes the size and energy level of the electron's orbital.
Angular momentum quantum number (l): Determines the shape of the electron's orbital (subshell, e.g., s, p, d, f).
Magnetic quantum number (ml): Describes the orientation of the orbital in space.
Quantum numbers of the orbitals in hydrogen are outlined.

Section 7.7: Orbital Shapes and Energies

Several different representations (visual and graphical) illustrate electron orbitals (1s, 2s, 3s and 2p, 3d, 4f).
Shapes are presented with boundary surfaces, and probability distributions.

Section 7.8: Electron Spin and the Pauli Principle

Electron spin quantum number (ms): Can have values of +½ or -½, representing the intrinsic spin of an electron.
Pauli exclusion principle: No two electrons in an atom can have the same set of four quantum numbers. This means each orbital can hold a maximum of two electrons with opposite spins.

Section 7.9: Polyelectronic Atoms

Atoms with multiple electrons have electron-electron repulsions. This makes accurate calculations of electron paths complex (Electron correlation problem).
Order of filling electron orbitals: Electrons prefer s, p, d, and then f orbitals in a given energy level.
Penetration effect: A 2s electron penetrates the nucleus more than a 2p electron, leading to a lower energy level for the 2s orbital in atoms with multiple electrons, compared to the 2p orbital.

Section 7.10: The History of the Periodic Table

The periodic table represents consistent patterns in element properties, such as their chemical reactivities.
Dmitri Mendeleev is credited for the current version, as he predicted the existence of elements not yet discovered based on the periodic table's patterns.

Section 7.11: The Aufbau Principle and the Periodic Table

Aufbau Principle: Electrons fill orbitals following a specific order based on increasing energy levels when atoms are being built.
Hund's Rule: The arrangement of electrons with maximum numbers of unpaired electrons in degenerate orbitals (same energy) will be the lowest energy configuration for the atom.
Orbital Diagrams provide a visual map of the electron configuration for an atom.
Valence electrons are the outermost electrons in an atom, determining its chemical properties.
Elements in the same group on the periodic table have the same valence electron configuration, and hence similar chemical properties.
Electron configurations for atoms such as sulfur, barium and europium outlined
Various parts of the periodic table are outlined, with examples.

Section 7.12: Periodic Trends in Atomic Properties

Ionization energy: energy needed to remove an electron. Trends are outlined for going across a period and down a group of the periodic table to show the pattern.
Electron affinity: energy change from adding an electron to an atom.
Atomic radius: radius of an atom. Trends are outlined for going across a period and down a group of the periodic table to show the pattern.
Comparisons between elements such as lithium and chlorine, iodine and cesium are shown
The effect of electron repulsions on the observed trends in ionization energy and radius.

Section 7.13: The Properties of a Group: The Alkali Metals

Valence electrons primarily dictate chemical behavior of atoms.
Periodic table organization can be used to predict electron configuration.
Different groups in the periodic table (special names like alkali metals, alkali earth metals etc.) are identified.
Differences between metals and nonmetals, and metalloids are shown.
Properties of alkali metals (Li, Na, K, Rb, Cs, and Fr) are discussed in terms of reactivity, ionization energy, atomic radius, density, and melting/boiling points. A comparison across the group shows general trends.

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Explore the concepts of atomic structure and periodicity in this quiz based on Chapter 7. Dive into the properties of elements and their arrangement in the periodic table, as well as the nature of electromagnetic radiation and its characteristics. Test your understanding of key concepts like wavelength, frequency, and the quantization of energy.