Question 1

Which of the following statements best explains why helium is used in modern blimps instead of hydrogen, as was used in the Hindenburg?

Accepted Answer

Helium is inert due to its full valence shell, making it non-reactive and safe, while hydrogen is highly reactive and flammable.

Question 2

A photon of ultraviolet (UV) light has a wavelength of $$200\ \mathrm{nm}$$, while a photon of infrared (IR) light has a wavelength of $$1000\ \mathrm{nm}. $$Which statement is correct regarding their energies?

Accepted Answer

The UV photon has higher energy because energy is inversely proportional to wavelength: $$E = \frac{hc}{\lambda}.$$

Question 3

Which of the following electron configurations represents a ground-state atom of aluminum (Al, atomic number 13)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^1$$

Question 4

Which of the following transitions in a hydrogen atom will emit a photon with the shortest wavelength?

Accepted Answer

From $$n=2 to$$ $$n=1$$

Question 5

Which of the following best describes the difference between an orbit in the Bohr model and an orbital in the quantum-mechanical model?

Accepted Answer

An orbit is a fixed path with a definite radius, while an orbital is a probability map indicating where an electron is likely to be found.

Question 6

Which element has the following electron configuration: $$[\mathrm{Ar}]\ 4s^2$\ 3d$$^{10}$$\ 4p^5$?

Accepted Answer

Bromine (Br)

Question 7

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{Na}^+$$

Question 8

Which of the following statements about periodic trends is correct?

Accepted Answer

Ionization energy decreases as you move down a group.

Question 9

A patient is undergoing radiation therapy for cancer. Which type of electromagnetic radiation is most likely being used, and why?

Accepted Answer

Gamma rays, because they have the highest energy and can damage biological molecules.

Question 10

Which of the following correctly lists the order of increasing energy per photon for the types of electromagnetic radiation?

Accepted Answer

Microwaves \u003c visible light \u003c X-rays

Question 11

Which of the following elements has the greatest metallic character?

Accepted Answer

Potassium (K)

Question 12

Which of the following statements about the filling of electron orbitals is correct?

Accepted Answer

Electrons fill orbitals of equal energy singly first with parallel spins, according to Hund's rule.

Question 13

Which of the following best explains why sodium ($$\mathrm{Na}) is $$highly reactive, while neon ($$\mathrm{Ne}) is $$inert?

Accepted Answer

Sodium has one valence electron and tends to lose it to achieve a noble gas configuration, while neon already has a full valence shell.

Question 14

Which of the following correctly describes the relationship between wavelength ($$\lambda$$), frequency ($$
u$$), and the speed of light ($$c$$)?

Accepted Answer

$$c = \lambda 
u$$

Question 15

Which of the following elements has the largest atomic radius?

Accepted Answer

Potassium (K)

Question 16

A sodium ion ($$\mathrm{Na}^+) $$and a potassium ion ($$\mathrm{K}^+) $$are both essential for nerve function. Which statement is correct regarding their relative sizes?

Accepted Answer

$$\mathrm{K}^+ is $$larger than $$\mathrm{Na}^+$$ because it is lower in the group and has more electron shells.

Question 17

Which of the following is the correct electron configuration for the $$\mathrm{Ca}^{2+}$$ ion?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$

Question 18

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have the same number of valence electrons and similar chemical properties.

Question 19

Which of the following colors of visible light has the highest energy per photon?

Accepted Answer

Violet

Question 20

A chemist is analyzing the emission spectrum of an unknown element and observes several bright lines at specific wavelengths. What does this indicate about the electronic structure of the element?

Accepted Answer

The element has quantized energy levels, and electrons transition between these levels, emitting photons of specific energies.

Ch 9: Electrons in Atoms and the Periodic Table: Light, Atomic Models, Electron Configurations, and Periodic Trends

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