Question 1

Which of the following statements best explains why the 1s electron in $$\mathrm{Li$$^{2+}$$} is $$harder to remove than the 1s electron in $$\mathrm{H}$$?

Accepted Answer

The 1s electron in $$\mathrm{Li$$^{2+}$$} is $$closer to the nucleus due to a higher nuclear charge, resulting in a stronger electrostatic attraction.

Question 2

In a many-electron atom, which factor primarily causes the energy of orbitals to differ from those in a one-electron atom?

Accepted Answer

Electron-electron repulsions

Question 3

Which quantum number is associated with the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number $$m_l$$

Question 4

According to the Pauli exclusion principle, what is the maximum number of electrons that can occupy a single orbital?

Accepted Answer

2

Question 5

Which of the following electron configurations represents a diamagnetic atom?

Accepted Answer

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

Question 6

Which rule states that electrons will fill degenerate orbitals singly before pairing up?

Accepted Answer

Hund's rule

Question 7

What is the ground-state electron configuration for a neutral sulfur atom ($$Z=16$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^4$$

Question 8

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

Accepted Answer

$$\mathrm{K^+}$$

Question 9

Why are cations generally smaller than their parent atoms?

Accepted Answer

Cations have fewer electrons, resulting in less electron-electron repulsion and a greater effective nuclear charge per electron.

Question 10

Which of the following best describes the order of orbital filling according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d \rightarrow 4p$$

Question 11

Which element has the ground-state electron configuration $$[\mathrm{Ar}]\ 4s^2$\ 3d^6$?

Accepted Answer

Fe

Question 12

What is the effective nuclear charge ($$Z_{\mathrm{eff}}) $$experienced by a 2s electron in lithium ($$\mathrm{Li}$$)?

Accepted Answer

$$Z_{\mathrm{eff}} is $$less than the actual nuclear charge due to shielding by the 1s electrons.

Question 13

Which of the following ions has the largest radius: $$\mathrm{K^+}$$, $$\mathrm{S$$^{2-}$$}$$, or $$\mathrm{Cl^-}$$?

Accepted Answer

$$\mathrm{S$$^{2-}$$}$$

Question 14

Which property is most directly related to the number of unpaired electrons in an atom or ion?

Accepted Answer

Paramagnetism

Question 15

Which experiment provided evidence for the existence of electron spin?

Accepted Answer

Stern-Gerlach experiment

Question 16

Which of the following best explains why the 2s orbital is lower in energy than the 2p orbital in a many-electron atom?

Accepted Answer

The 2s orbital has greater penetration, allowing its electrons to be closer to the nucleus and experience less shielding.

Question 17

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

Accepted Answer

$$[\mathrm{Ar}]\ 3d^6$

Question 18

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

Accepted Answer

Elements in the same group have similar valence electron configurations.

Question 19

Which of the following best describes the electron configuration of a $$\mathrm{Cr$$^{3+}$$}$$ ion?

Accepted Answer

$$[\mathrm{Ar}]\ 3d^3$

Lec 5 notes chem

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