CEM 141 – Chapter 2 Study Notes

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Questions and Answers

What describes the relationship between wavelength and frequency in electromagnetic radiation?

They are directly proportional.

Wavelength increases as frequency increases.

They are independent of each other.

Wavelength decreases as frequency increases. (correct)

Which component of electromagnetic radiation refers to the height of the peaks?

Amplitude (correct)

Wavelength

Frequency

Energy

In the speed of light equation, which variable represents wavelength?

λ (correct)

Which type of electromagnetic radiation has the highest energy?

X-rays Signup and view all the answers

Why do He atoms interact through London Dispersion Forces (LDFs) instead of forming covalent bonds?

He is a noble gas with a complete electron shell. Signup and view all the answers

What happens to the energy of light as its frequency increases?

It increases. Signup and view all the answers

Which wavelength is most likely associated with red light?

700 nm Signup and view all the answers

Which statement is true regarding light?

Light exhibits both wave and particle properties. Signup and view all the answers

Which statement accurately describes core electrons?

They do not participate in chemical reactions. Signup and view all the answers

What is the electron configuration for chlorine (Cl)?

[Ne] 3s2 3p5 Signup and view all the answers

According to the Aufbau principle, how are electrons added to orbitals?

From lower energy to higher energy orbitals. Signup and view all the answers

How many valence electrons does phosphorus (P) have?

5 Signup and view all the answers

Which of the following elements is classified as a p-block element?

Chlorine (Cl) Signup and view all the answers

What is the core and valence electron configuration for oxygen (O)?

Core: 2, Valence: 4 Signup and view all the answers

According to Hund's Rule, what is the correct way to fill orbitals?

Single electrons must occupy each orbital before pairing occurs. Signup and view all the answers

What is the total number of core and valence electrons in bromine (Br)?

28 core, 7 valence Signup and view all the answers

What is the reason for the significant increase in the third ionization energy of magnesium?

Change from valence to core electron removal Signup and view all the answers

Which factor contributes most significantly to the increase in ionization energy as more electrons are removed from an atom?

Decreased electron shielding Signup and view all the answers

Given the trend in ionization energies, which element in period three is likely to have the highest first ionization energy?

Phosphorus (P) Signup and view all the answers

Which of the following statements about ionization energies is true?

Ionization energy increases with the removal of each successive electron. Signup and view all the answers

What trend is observed in the successive ionization energies of magnesium based on the provided values?

There are large jumps in energy required for successive ionizations. Signup and view all the answers

What does the Bohr model suggest about the movement of electrons?

Electrons are found in fixed orbits with defined energy levels. Signup and view all the answers

What is a key feature of the energy levels in the Bohr model?

Energy levels have associated quantum numbers. Signup and view all the answers

What happens when an electron transitions to a higher energy level?

A photon is absorbed. Signup and view all the answers

What is the result of an electron moving to a lower energy level?

A photon is emitted. Signup and view all the answers

Which of the following does the Bohr model NOT successfully explain?

Energy transitions in multi-electron atoms. Signup and view all the answers

How are the energies of photons related to electron transitions?

Equal to the difference in energy between two energy levels. Signup and view all the answers

What misconception about energy levels does the Bohr model address?

Energy levels are the same as physical orbits. Signup and view all the answers

Which of the following describes the concept of quantum numbers in relation to Bohr's model?

Quantum numbers are used to define allowed energy levels. Signup and view all the answers

What evidence supports the wave nature of electrons?

Interference pattern of electrons passing through Al foil Signup and view all the answers

What fundamental principle states that we cannot know both the position and energy of an electron accurately?

Heisenberg Uncertainty Principle Signup and view all the answers

How does the quantum model of the atom differ from the Bohr model regarding electrons?

Electrons are treated as waves in the quantum model Signup and view all the answers

During the double slit experiment, what do electrons display that indicates their wave properties?

Interference patterns Signup and view all the answers

What must be true about the energy of electrons in an atom according to modern quantum theory?

Electrons can only have certain quantized energies Signup and view all the answers

What does the revival of Schrödinger's work represent in terms of electron behavior in atoms?

Incorporating wave mechanics into atomic theory Signup and view all the answers

Which of the following statements about the Bohr model is true?

It is based on classical physics with circular orbits. Signup and view all the answers

In relation to atomic structure, how are the positions of electrons described in quantum mechanics?

Electrons exist in probabilistic clouds of locations. Signup and view all the answers

Study Notes

Electrons and Orbitals

Understanding the atomic structure requires knowledge of where electrons are located and their influence on element properties.
Electrons in helium interact through London Dispersion Forces (LDFs), while hydrogen forms covalent bonds.

Electromagnetic Radiation

Electromagnetic radiation refers to waves of electric and magnetic fields, seen in various forms such as radio waves and X-rays.
Key characteristics include wavelength (λ) in meters and frequency (ν) in Hertz (Hz).
The speed of light (c) is a constant at 3.00 × 10^8 m/s, governing the relationship λ × ν = c.
Energy of light increases with frequency and decreases with increasing wavelength, unaffected by amplitude.

Bohr Model of the Atom

Developed by Niels Bohr, suggesting electrons move in fixed orbits around the nucleus, each with a specific energy level.
Electrons transition between energy levels by absorbing or emitting photons; energy of photons corresponds to the energy difference between levels.

Limitations of the Bohr Model

Works only for hydrogen and does not account for other elements, necessitating a move to a more complex model.
Electrons are not in defined orbits, as illustrated by the Heisenberg Uncertainty Principle, which states simultaneous measurement of energy and position isn't possible.

Quantum Mechanics and Orbitals

Erwin Schrödinger’s application of quantum mechanics describes electrons as wave-like entities.
Atomic orbitals represent regions around the nucleus where electrons are likely to be found, with each orbital having a specific energy level.
Orbitals are not literal orbits but energy levels; quantized energy levels determine electron behavior.

Electron Configuration

Understanding valence and core electrons is crucial; core electrons comprise closed shells that are stable and unreactive, while valence electrons influence chemical reactivity.
Electron configurations detail the distribution of electrons across orbitals, with notation indicating the last noble gas and any remaining electrons.

Ionization Energies

Ionization energy (IE) is influenced by effective nuclear charge, atomic size, and the shell from which an electron is removed.
Observing trends in ionization energy provides insights into element reactivity and stability, with notable jumps indicating the removal of core electrons.

Practical Applications

Students should be able to write electron configurations for various elements, understand the concept of core versus valence electrons, and explain ionization processes and trends among elements.
Encouraged to engage during lectures for insights beyond these notes, including questions regarding complex topics like Schrödinger's cat.

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Description

This quiz covers the essential内容 from Chapter 2 of CEM 141. It emphasizes the importance of taking detailed notes during lectures, including answers to questions and additional explanations. Use these concise notes as a foundation for further study and seek clarification during office hours.