Question 1

Which principle states that electrons are added to the lowest energy orbitals first when building up the electron configuration of an atom?

Accepted Answer

Aufbau Principle

Question 2

What is the ground-state electron configuration for a neutral sodium (Na) atom?

Accepted Answer

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

Question 3

Which of the following ions is isoelectronic with neon ($$Ne$$)?

Accepted Answer

$$Na^+$$

Question 4

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

Accepted Answer

5

Question 5

Which electron configuration represents a transition metal with a completely filled $$d$$ subshell?

Accepted Answer

$$[Ar]\ 4s^2$\ 3d$$^{10}$$

Question 6

Which rule states that no two electrons in an atom can have the same set of four quantum numbers?

Accepted Answer

Pauli Exclusion Principle

Question 7

What is the shorthand electron configuration for selenium ($$Se$$)?

Accepted Answer

$$[Ar]\ 4s^2$\ 3d$$^{10}$$\ 4p^4$

Question 8

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

Accepted Answer

Iron ($$Fe)$$

Question 9

When forming cations, which electrons are lost first in transition metals?

Accepted Answer

Electrons from the $$s$$ subshell of the highest principal quantum number

Question 10

Which of the following ions is diamagnetic?

Accepted Answer

$$Zn^{2+}$$

Question 11

According to Hund's Rule, when filling degenerate orbitals, electrons will:

Accepted Answer

Fill each orbital singly with parallel spins before pairing

Question 12

What is the charge of the ion formed by a Group 2A alkaline earth metal?

Accepted Answer

2+

Question 13

Which of the following elements has a ground-state electron configuration ending in $$3p^3$$?

Accepted Answer

Phosphorus ($$P)$$

Question 14

How many valence electrons does nickel ($$Ni) $$have, according to its electron configuration $$[Ar]\ 4s^2$\ 3d^8$?

Accepted Answer

10

Question 15

Which of the following is the correct electron configuration for the $$Cl^-$$ ion?

Accepted Answer

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

Question 16

Which of the following statements about noble gases is TRUE?

Accepted Answer

They have a completely filled highest principal energy level

Question 17

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

Accepted Answer

$$[Ar]\ 3d^6$

Question 18

Which of the following elements is paramagnetic in its ground state?

Accepted Answer

Iron ($$Fe)$$

Question 19

Which of the following best explains why $$4s$$ electrons are lost before $$3d$$ electrons when transition metals form cations?

Accepted Answer

The $$4s$$ orbital is higher in energy than the $$3d$$ orbital after electron filling

Question 20

Which of the following ions has the same number of electrons as $$Ar$$?

Accepted Answer

$$Cl^-$$

Electron Configuration, Quantum Numbers, and Periodic Table Structure

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