Question 1

According to the Bohr model, electrons occupy specific energy levels around the nucleus. Which statement best describes the arrangement of these energy levels?

Accepted Answer

Energy levels are quantized and increase in energy as they move farther from the nucleus.

Question 2

Which of the following correctly lists the sublevels present in the third energy level ($$n=3) of an $$atom?

Accepted Answer

$$3s$$, $$3p$$, $$3d$$

Question 3

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

Accepted Answer

6

Question 4

Which equation correctly represents the maximum number of electrons in a principal energy level $$n$$?

Accepted Answer

$$2n^2$$

Question 5

An atom of sulfur ($$S) $$has an atomic number of 16. What is its electron configuration?

Accepted Answer

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

Question 6

Which of the following elements has the smallest atomic radius?

Accepted Answer

Cl

Question 7

How many valence electrons does an atom of phosphorus ($$P) $$have?

Accepted Answer

5

Question 8

Which group in the periodic table contains elements with 2 valence electrons?

Accepted Answer

Group 2 (alkaline earth metals)

Question 9

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

Accepted Answer

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

Question 10

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

Accepted Answer

The number of protons increases, pulling electrons closer to the nucleus.

Question 11

Which sublevel can hold a maximum of 10 electrons?

Accepted Answer

$$d$$

Question 12

If an atom has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^5$$, what element is it?

Accepted Answer

Chlorine ($$Cl)$$

Question 13

Which of the following ions has the same electron configuration as neon ($$Ne$$)?

Accepted Answer

$$Na^+$$

Question 14

What is the total number of sublevels in the fourth energy level ($$n=4$$)?

Accepted Answer

4

Question 15

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

Accepted Answer

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

Question 16

A magnesium atom ($$Mg) $$loses two electrons to form $$Mg^{2+}. $$What is the resulting electron configuration?

Accepted Answer

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

Question 17

Which element is most likely to form a $$-1$$ ion based on its position in the periodic table?

Accepted Answer

Chlorine ($$Cl)$$

Question 18

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons are responsible for chemical bonding.

Question 19

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

Accepted Answer

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

Question 20

Which block of the periodic table contains elements whose last electron enters a $$d$$ sublevel?

Accepted Answer

d-block

Electron Configurations and Periodic Trends: Study Notes

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