Question 1

Which of the following statements best describes the relationship between the principal quantum number $$n$$ and the energy level of an atom?

Accepted Answer

As $$n$$ increases, both the energy level and the size of the orbital increase.

Question 2

What is the electron arrangement for the element Calcium ($$Z = 20$$)?

Accepted Answer

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

Question 3

Which of the following elements has a completely filled $$2p$$ subshell?

Accepted Answer

Neon ($$Z = 10)$$

Question 4

The energy levels (shell numbers) of an atom can be tied to the ______ of the Periodic Table.

Accepted Answer

periods

Question 5

If an atom has 11 electrons, what is its electron configuration?

Accepted Answer

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

Question 6

Which of the following is true about elements with atomic numbers greater than 20?

Accepted Answer

They have partially filled $$d$$ and $$f$$ orbitals, which are beyond the scope of introductory GOB Chemistry.

Question 7

Which of the following best explains why the energy of an orbital increases as the principal quantum number $$n$$ increases?

Accepted Answer

Higher $$n$$ means electrons are farther from the nucleus, requiring more energy to remain bound.

Question 8

Which element has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^5$$?

Accepted Answer

Chlorine ($$Z = 17)$$

Question 9

Which of the following statements is correct regarding the filling order of electron orbitals?

Accepted Answer

Electrons fill the $$4s$$ orbital before the $$3d$$ orbital.

Question 10

A patient is found to have a deficiency in sodium ($$Z = 11). $$What is the electron configuration for sodium, and why is it chemically reactive?

Accepted Answer

Sodium has the configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^1$$; it is reactive because it has one electron in its outermost shell, which it readily loses to achieve a stable noble gas configuration.

Question 11

Which of the following elements is in the same period as magnesium ($$Z = 12$$)?

Accepted Answer

Sodium ($$Z = 11)$$

Question 12

How many electrons are present in the third energy level (shell) of phosphorus ($$Z = 15$$)?

Accepted Answer

5

Question 13

Which of the following is the correct electron configuration for argon ($$Z = 18$$)?

Accepted Answer

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

Question 14

Which of the following elements has the highest number of electrons in its outermost shell among the first 20 elements?

Accepted Answer

Argon ($$Z = 18)$$

Question 15

Which of the following is a correct statement about the periodic table and electron arrangement?

Accepted Answer

Elements in the same period have the same number of energy levels.

Question 16

A medical technologist is analyzing potassium ($$Z = 19) in a $$blood sample. What is the electron configuration for potassium?

Accepted Answer

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

Question 17

Which of the following elements has a valence electron configuration of $$2s^2$$\ $$2p^3$$?

Accepted Answer

Nitrogen ($$Z = 7)$$

Question 18

Which of the following is the correct electron configuration for aluminum ($$Z = 13$$)?

Accepted Answer

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

Question 19

Which of the following elements has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^4$$?

Accepted Answer

Sulfur ($$Z = 16)$$

Electron Arrangement and Energy Levels in Atoms

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