Question 1

Which quantum number primarily determines the energy level of an electron in an atom, and what are its allowed values?

Accepted Answer

The principal quantum number $$n$$, with allowed values $$n = 1, 2, 3, \ldots$$

Question 2

Which orbital type is spherical in shape and what is its corresponding azimuthal quantum number $$l$$?

Accepted Answer

s orbital, $$l = 0$$

Question 3

According to the Pauli Exclusion Principle, what is true about the quantum numbers of electrons in the same atom?

Accepted Answer

No two electrons can have the same set of all four quantum numbers ($$n$$, $$l$$, $$m_l$$, $$m_s)$$

Question 4

Which of the following electron configurations represents the ground state of fluorine ($$Z=9$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^5$$

Question 5

Which statement best explains why the atomic radius decreases across a period from left to right?

Accepted Answer

Increasing nuclear charge pulls electrons closer to the nucleus

Question 6

What is the electron configuration for the $$Fe^{2+}$$ ion?

Accepted Answer

$$[Ar]\ 3d^6$

Question 7

Which of the following ions is smallest in an isoelectronic series: $$O^{2-}$$, $$F^{-}$$, $$Na^{+}$$, $$Mg^{2+}$$?

Accepted Answer

$$Mg^{2+}$$

Question 8

Why does the electron configuration of chromium ($$Z=24) $$deviate from the expected pattern?

Accepted Answer

Half-filled $$d$$ subshells are more stable, so one electron from $$4s is $$promoted to $$3d$$

Question 9

Which quantum number describes the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number $$m_l$$

Question 10

What is the maximum number of electrons that can occupy the $$3p$$ subshell?

Accepted Answer

$$6$$

Question 11

Which element has the electron configuration $$[Ne]\ 3s^2$\ 3p^5$?

Accepted Answer

Chlorine

Question 12

Which of the following statements about ionization energy is correct?

Accepted Answer

Ionization energy generally increases across a period

Question 13

What is the condensed electron configuration for potassium ($$Z=19$$)?

Accepted Answer

$$[Ar]\ 4s^1$

Question 14

Which of the following best describes the difference between core and valence electrons?

Accepted Answer

Valence electrons are in the outermost shell and participate in chemical bonding; core electrons are in filled inner shells

Question 15

Which of the following ions has the same electron configuration as neon?

Accepted Answer

$$F^{-}$$

Question 16

What is the electron configuration for the $$N^{3-}$$ ion?

Accepted Answer

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

Question 17

Which of the following best explains why anions are larger than their parent atoms?

Accepted Answer

Adding electrons increases electron-electron repulsion, expanding the electron cloud

Question 18

Which element is most likely to form a cation?

Accepted Answer

Sodium

Question 19

Which quantum number is responsible for the 'shape' of an orbital?

Accepted Answer

Azimuthal quantum number $$l$$

Question 20

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity generally increases across a period, with some exceptions

Electronic Structure of Atoms: Quantum Numbers, Orbitals, and Electron Configurations

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