Which Of The Following Is An Isoelectronic Series

Unlocking the Secrets of Isoelectronic Series

Are you curious about the enigmatic world of chemistry, where electrons dance harmoniously around atoms? One captivating concept is the isoelectronic series, a collection of elements or ions that share an identical number of electrons. Join us as we delve into which of the following is an isoelectronic series and explore its fascinating implications.

Unveiling the Enigma

Determining which compounds belong to an isoelectronic series can be a puzzling endeavor. It requires a keen eye for atomic structures and an understanding of electron configurations. Each element or ion in an isoelectronic series has a distinctive arrangement of electrons that bestows upon them similar chemical properties and reactivity.

Solving the Mystery

After meticulous scrutiny, we can confidently unveil the isoelectronic series from the given options: [Co(NH3)6]3+, [Fe(CN)6]4-, and [Cr(H2O)6]3+. These three compounds all possess a total of 36 electrons, resulting in an identical electron configuration and comparable chemical behavior.

Unifying Insights

In summary, an isoelectronic series encompasses a group of elements or ions with the same number of electrons. This commonality leads to striking similarities in their chemical properties and reactivity. Understanding isoelectronic series allows chemists to make predictions about the behavior of unknown species and provides insights into the underlying principles governing their interactions.

Which Of The Following Is An Isoelectronic Series

Isoelectronic Series


An isoelectronic series refers to a group of atoms, ions, or molecules that possess the same number of electrons. This commonality in electron count results in similar chemical properties and structural characteristics.

Isoelectronic Ions


  • Na+ (sodium ion), Mg2+ (magnesium ion), Al3+ (aluminum ion), Si4+ (silicon ion)
  • Cl- (chloride ion), S2- (sulfide ion), P3- (phosphide ion), Ar (argon atom)

Isoelectronic Molecules


  • CO (carbon monoxide), N2 (nitrogen molecule), O2 (oxygen molecule)
  • CH4 (methane), NH3 (ammonia), H2O (water)

Isoelectronic Series and Chemical Properties

Chemical Bonding:

  • Isoelectronic species have similar valence electron configurations, which influence their chemical bonding tendencies.
  • For example, the isoelectronic ions Na+, Mg2+, and Al3+ all form ionic bonds due to their positive charges.


  • The reactivity of isoelectronic species is comparable because they possess the same number of electrons in their outermost energy level.
  • For instance, the isoelectronic molecules CO, N2, and O2 are all relatively unreactive gases.

Size and Shape:

  • Isoelectronic species typically have similar atomic or molecular radii.
  • This is because the increased nuclear charge (for ions) or protons (for molecules) is offset by the increased number of electrons.

Examples of Isoelectronic Series

Noble Gas Elements:

  • The noble gases (Group 18) form an isoelectronic series because they all have eight valence electrons.

Halogens and Chalcogens:

  • The halogens (Group 17) and chalcogens (Group 16) elements form isoelectronic series based on shared valence electron configurations.

Carbonate and Nitrate Ions:

  • The carbonate ion (CO32-) and nitrate ion (NO3-) are isoelectronic and have similar structural arrangements.

Importance of Isoelectronic Series

Understanding Chemical Bonding:

  • Isoelectronic series provide insights into the relationship between electron configuration and chemical bonding.

Predicting Properties:

  • By comparing isoelectronic species, scientists can predict the properties of unknown compounds based on their similarities to known substances.

Spectroscopic Analysis:

  • Isoelectronic series can be used to interpret spectroscopic data, as they exhibit similar spectral patterns.


Isoelectronic series are a valuable concept in chemistry that helps us understand the relationship between electron configuration and chemical properties. By studying these series, scientists can gain insights into the behavior of atoms, ions, and molecules, and make predictions about their reactivity and structure.


  1. What is the difference between isoelectronic ions and isoelectronic molecules?
  • Isoelectronic ions have different charges but the same number of electrons, while isoelectronic molecules have the same number of electrons and protons.
  1. How do you determine if a group of species is isoelectronic?
  • Count the total number of electrons in each species and compare them.
  1. Why are isoelectronic series important in chemistry?
  • They help us understand chemical bonding, predict properties, and interpret spectroscopic data.
  1. Give an example of an isoelectronic series with more than three members.
  • The noble gases (He, Ne, Ar, Kr, Xe, Rn) are all isoelectronic.
  1. How can isoelectronic series help predict the properties of an unknown compound?
  • By comparing the isoelectronic series to known compounds with similar electron configurations, we can infer similarities in their properties.



You May Also Like