Q: Which of the following best describes the difference between a Bohr model and a quantum mechanical model of the atom?

The Bohr model uses fixed orbits, while the quantum model uses probability distributions for electron locations.

Q: Which of the following particles is emitted during positron emission?

A particle with the same mass as an electron but with a positive charge.

Q: Which of the following best explains why noble gases are generally unreactive?

They have a full valence shell of electrons.

Q: A radioactive isotope undergoes gamma emission. What changes occur in the nucleus?

No change in atomic number or mass number; only energy is released.

Question 1

Which of the following best explains why the first ionization energy generally increases across a period from left to right in the periodic table?

Accepted Answer

The nuclear charge increases while shielding remains relatively constant, increasing the attraction between nucleus and valence electrons.

Question 2

A neutral atom of phosphorus ($Z = 15$) has how many valence electrons?

Accepted Answer

$5$

Question 3

Which electron configuration represents a sodium ion ($\mathrm{Na^+}$)?

Accepted Answer

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

Question 4

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

Accepted Answer

Electrons occupy fixed orbits with quantized energies around the nucleus.

Question 5

Which element would you expect to have the highest first ionization energy?

Accepted Answer

Neon ($\mathrm{Ne}$)

Question 6

Given the shorthand electron configuration $[Ar]\ 4s^2\ 3d^6$, how many electrons does this atom have?

Accepted Answer

$26$

Question 7

Which of the following best describes a beta decay process?

Accepted Answer

A neutron in the nucleus converts into a proton and emits an electron.

Question 8

Which of the following is the correct electron configuration for an oxygen atom ($Z = 8$)?

Accepted Answer

$1s^2\ 2s^2\ 2p^4$

Question 9

A certain atom has 17 protons, 18 neutrons, and 17 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number $17$, mass number $35$

Question 10

Which of the following is a correct statement about fission and fusion reactions?

Accepted Answer

Fission splits a heavy nucleus into smaller nuclei, while fusion combines light nuclei to form a heavier nucleus.

Question 11

Which of the following best describes the trend in atomic radius as you move down a group in the periodic table?

Accepted Answer

Atomic radius increases due to addition of energy levels.

Question 12

Which of the following elements is most likely to undergo alpha decay?

Accepted Answer

Uranium ($\mathrm{U}$)

Question 13

Which quantum number determines the shape of an orbital?

Accepted Answer

Azimuthal quantum number ($l$)

Question 14

Which of the following is the correct order of electromagnetic radiation from lowest to highest energy?

Accepted Answer

Radio < Visible < Gamma

Question 15

If an atom has the electron configuration $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^1$, what is the element?

Accepted Answer

Aluminum ($\mathrm{Al}$)

Question 16

Which of the following best describes the difference between a Bohr model and a quantum mechanical model of the atom?

Accepted Answer

The Bohr model uses fixed orbits, while the quantum model uses probability distributions for electron locations.

Question 17

Which of the following is the correct shorthand electron configuration for iron ($Z = 26$)?

Accepted Answer

$[Ar]\ 4s^2\ 3d^6$

Question 18

Which of the following particles is emitted during positron emission?

Accepted Answer

A particle with the same mass as an electron but with a positive charge.

Question 19

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 20

A radioactive isotope undergoes gamma emission. What changes occur in the nucleus?

Accepted Answer

No change in atomic number or mass number; only energy is released.

Atomic Structure, Periodic Trends, and Nuclear Chemistry: Study Notes

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