Question 1

Which quantum number determines the overall size and energy of an atomic orbital?

Accepted Answer

The principal quantum number $$n$$

Question 2

How many radial nodes are present in a 4p orbital?

Accepted Answer

$$n - l - 1 = 4 - 1 - 1 = 2$$

Question 3

Which of the following sets of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$(n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2})$$

Question 4

Which orbital has the greatest penetration and therefore the lowest energy in a multi-electron atom?

Accepted Answer

$$3s$$

Question 5

What is the maximum number of electrons that can occupy the $$n=4$$ energy level?

Accepted Answer

32

Question 6

Which element has the ground state electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^5$$?

Accepted Answer

Bromine (Br)

Question 7

Which rule is violated if two electrons in the same orbital have the same spin?

Accepted Answer

Pauli exclusion principle

Question 8

What is the abbreviated (noble gas) electron configuration for Tin (Sn)?

Accepted Answer

$$[Kr] 5s^2$ 4d$$^{10}$$ 5p^2$

Question 9

Which of the following statements about Mendeleev’s periodic table is TRUE?

Accepted Answer

He left gaps for undiscovered elements and predicted their properties.

Question 10

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 bonding.

Question 11

How many electrons can occupy all the $$d$$ orbitals in a single principal energy level?

Accepted Answer

10

Question 12

Which of the following ions has the same electron configuration as Argon ($$Ar$$)?

Accepted Answer

$$Cl^-$$

Question 13

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

Accepted Answer

2s electrons penetrate closer to the nucleus and experience a higher effective nuclear charge.

Question 14

Which of the following is the correct order of filling for the following orbitals according to the Aufbau principle?

Accepted Answer

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

Question 15

Which of the following is a valid set of quantum numbers for an electron in a 3d orbital?

Accepted Answer

$$n=3,\ l=2,\ m_l=2,\ m_s=+\frac{1}{2}$$

Question 16

Which of the following best describes the periodic law?

Accepted Answer

When elements are arranged by increasing atomic mass, certain properties recur periodically.

Question 17

What is the maximum number of electrons that can occupy the 4f sublevel?

Accepted Answer

14

Question 18

Which of the following best explains why electrons fill the 4s orbital before the 3d orbital?

Accepted Answer

The 4s orbital is lower in energy than the 3d orbital due to sublevel splitting.

Question 19

Which of the following is the correct electron configuration for the $$Cr$$ atom (chromium, atomic number 24)?

Accepted Answer

$$[Ar] 4s^1$ 3d^5$

Periodic Properties of Elements and Quantum Mechanical Model: Study Notes

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