Electron Configuration Practice

Which electron configuration shows a violation of Hund's Rule?

• A only

• A, B and C

• C and A

• A, B and D

Answer explanation

Hund's Rule states that electrons must occupy degenerate orbitals singly before pairing. Configurations A, B, and D violate this rule by pairing electrons in orbitals before all have been singly occupied.

Tags

NGSS.HS-PS1-1

What rule(s) do you need to know for Electron Configuration?

• Aufbau Principle only

• Pauli Exclusion Principle only

• Hund's Rule only

• All three of them

Answer explanation

To understand electron configuration, you need to know the Aufbau Principle (filling order), Pauli Exclusion Principle (no two electrons can have the same set of quantum numbers), and Hund's Rule (maximize unpaired electrons in orbitals). All three are essential.

Within an energy level, which sublevel is the lowest in energy?

• s

• f

• d

• p

Answer explanation

The s sublevel is the lowest in energy within an energy level. It can hold a maximum of 2 electrons and is filled before the p, d, and f sublevels, which have higher energy.

What is incorrect about this orbital diagram?

• Both arrows in the 1st 2p orbital should be pointing up

• There is nothing incorrect with this diagram

• In the 2p energy level, each of the arrow should be in separate orbital, with each pointing upwards.

• All the arrows should be pointing up.

Answer explanation

In the 2p energy level, each electron should occupy separate orbitals with parallel spins (arrows pointing up) before pairing. The diagram incorrectly shows both arrows in the same orbital.

The electron-configuration notation for sodium (Na) is 1s² 2s² 2p⁶ 3s¹. Which of these options is the correct orbital notation for Sodium?

• 
• 
• 
• 

Tags

NGSS.HS-PS1-1

In writing the noble gas notation for elements in the 4th period, which noble gas will be used?

• Period 1 noble gas (Helium)

• Period 2 noble gas (Neon)

• Period 3 noble gas (Argon)

• Period 4 noble gas (Krypton)

Answer explanation

In noble gas notation, we use the nearest preceding noble gas. For elements in the 4th period, the noble gas is Argon (Period 3), as it is the closest noble gas before the 4th period elements.

Tags

NGSS.HS-PS1-1

Which of these IS NOT a way to indicate electron configuration?

• Orbital Notation

• Electron-configuration Notation

• Noble gas Notation

• Alkaline-earth Notation

Answer explanation

Alkaline-earth Notation is not a recognized method for indicating electron configuration. The other options—Orbital Notation, Electron-configuration Notation, and Noble gas Notation—are valid ways to represent electron arrangements.

How many valence electrons does Si contain? (click to see image)

• 14

• 28

• 2

• 4

Answer explanation

Silicon (Si) is in group 14 of the periodic table, which means it has 4 valence electrons. This is the correct choice, as the other options do not represent the number of valence electrons for silicon.

Tags

NGSS.HS-PS1-1

What atom is represented here?

• Carbon

• Nitrogen

• Oxygen

• Fluorine

Answer explanation

The atom represented is Nitrogen, which has the atomic number 7. It is essential for life and is found in amino acids and nucleic acids, distinguishing it from Carbon (6), Oxygen (8), and Fluorine (9).

Tags

NGSS.HS-PS1-1

What is the electron configuration for this atom?

• 1s²2s²2p⁶

• 1s²2s²2p⁵

• 1s²2s²2p³

• 2s²2p³

Answer explanation

The correct electron configuration for an atom with 15 electrons (like phosphorus) is 1s² 2s² 2p⁶ 3s² 3p³. However, the question asks for the configuration up to 2p, which is 1s² 2s² 2p³.

Tags

NGSS.HS-PS1-1