How to Predict an Element from Its Ionization Enthalpies and Electron Gain Enthalpy – Part 1

The energy required to remove an electron (e─) from the isolated atom/ion in the gaseous state of an element to form a cation is referred to as the ionization energy/enthalpy/potential (IE/IP).


For an element, IE involves an endothermic reaction; and in general, IE3 > IE2 > IE1.

The energy released to add an e─ to the isolated atom/ion in the gaseous state of an element to form an anion is known as the electron affinity (EA) or electron gain enthalpy.

For an element, EA involves an exothermic reaction.

Question:

The first (ΔiH1) and the second (ΔiH2) ionization enthalpies (in kJ mol–1) and the (ΔegH) electron gain enthalpy (in kJ mol–1) of a few elements are given below:

Element

ΔiH1

ΔiH2

ΔegH

I

520

7300

─60

II

419

3051

─48

III

1681

3374

─328

IV

1008

1846

─295

V

2372

5251

+48

VI

738

1451

─40

Which of the above elements is likely to be:

  1. the least reactive element
  2. the most reactive metal
  3. the most reactive non-metal
  4. the least reactive non-metal
  5. the metal which can form a stable binary halide of the formula MX2 (X = Halogen)
  6. the metal which can form a predominantly stable covalent halide of the formula MX (X = Halogen)?

Solution:



Click/tap to enlarge the image

* This column is for comments and not for conclusions. The elements cannot be concluded from the given information.

Irate by ionization❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

‌(1)    Ncert. Chemistry : Textbook for Class XI - Part.I; National Council Of Educational Research And Training: New Delhi.

(2)    Brown, C.; Ford, M. Higher Level Chemistry, 2nd ed.; Pearson Education: Harlow, Essex, 2014.

(3)    Wikipedia. Ionization energy. Wikipedia. https://en.wikipedia.org/wiki/Ionization_energy.

‌(4)    Ionization energies of the elements (data page). Wikipedia. https://en.wikipedia.org/wiki/Ionization_energies_of_the_elements_(data_page).

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