The successive ionization energies for an element are 735, 1445, 7730, 11600 eV. To which group does it belong?

1. The successive ionization energies for an element are 735, 1445, 7730, 11600 eV. To which group does it belong? +

Correct Answer

Group 2 — Alkaline Earth Metals

Detailed Solution

The successive ionization energies are:

IE₁ = 735
IE₂ = 1445
IE₃ = 7730
IE₄ = 11600

Now compare the successive values. The important observation is the very large jump between the second and third ionization energies:

IE₂ = 1445 → IE₃ = 7730

Huge jump occurs after removal of 2 electrons.

This means the atom can lose two electrons relatively easily, but removal of the third electron requires much more energy because the third electron belongs to an inner, stable shell. Therefore, the element has:

2 valence electrons

Elements having two valence electrons belong to:

Group 2

These are called the alkaline earth metals.

JEE Shortcut

In successive ionization-energy questions, locate the largest sudden jump.

IE₁ → IE₂ → IE₃

Since the huge jump occurs after the second ionization, the atom has 2 valence electrons.

Number of ionizations before the big jump = Number of valence electrons

Hence:

2 valence electrons → Group 2

Electronic Configuration Idea

A Group 2 element generally has an outer configuration:

ns²

The first two electrons are relatively easy to remove:

M → M⁺ → M²⁺

After this, the third electron is a core electron. Removing it requires exceptionally high energy. Thus:

IE₁ < IE₂ ≪ IE₃

This confirms Group 2.

Important Note

The numerical values in standard chemistry tables are normally reported in kJ mol⁻¹, not eV. The group-identification logic, however, depends on the large jump between IE₂ and IE₃, so the answer remains Group 2.

30 Related MCQs with Solutions

1. If the large jump in successive ionization energies occurs after IE₂, the element belongs to:

A. Group 1

B. Group 2

C. Group 13

D. Group 14

Answer: B. Group 2
Two electrons are removed before the core-electron jump.

2. A large jump after IE₁ indicates:

A. 1 valence electron

B. 2 valence electrons

C. 3 valence electrons

D. 4 valence electrons

Answer: A

3. A large jump after IE₃ indicates how many valence electrons?

A. 1

B. 2

C. 3

D. 4

Answer: C. 3

4. For a Group 2 element, the general outer configuration is:

A. ns¹

B. ns²

C. ns²np¹

D. ns²np²

Answer: B. ns²

5. The given ionization energies show the largest jump between:

A. IE₁ and IE₂

B. IE₂ and IE₃

C. IE₃ and IE₄

D. None

Answer: B

6. The big jump in IE occurs because:

A. A valence electron is being removed

B. A core electron starts being removed

C. Atomic mass increases

D. Neutrons are removed

Answer: B

7. Which group contains alkaline earth metals?

A. Group 1

B. Group 2

C. Group 17

D. Group 18

Answer: B

8. Which element is a typical Group 2 element?

A. Na

B. Mg

C. Al

D. Si

Answer: B. Mg

9. For Mg, the major jump occurs between:

A. IE₁ and IE₂

B. IE₂ and IE₃

C. IE₃ and IE₄

D. IE₄ and IE₅

Answer: B

10. An element with configuration [Ne]3s² belongs to:

A. Group 1

B. Group 2

C. Group 13

D. Group 18

Answer: B

11. If the jump occurs after IE₄, the element has:

A. 2 valence electrons

B. 3 valence electrons

C. 4 valence electrons

D. 5 valence electrons

Answer: C

12. The first ionization removes:

A. The first electron from gaseous atom

B. The first proton

C. The first neutron

D. A nucleus

Answer: A

13. Successive ionization enthalpies generally:

A. Decrease continuously

B. Increase successively

C. Remain equal

D. Become zero

Answer: B

14. Which has two valence electrons?

A. Na

B. Mg

C. Al

D. Cl

Answer: B. Mg

15. The third ionization of a Group 2 element involves removal of:

A. A valence electron

B. A core electron

C. A neutron

D. A proton

Answer: B

16. The sudden increase in IE indicates:

A. Transition from valence-electron removal to core-electron removal

B. Addition of a shell

C. Addition of a proton only

D. Decrease in nuclear charge

Answer: A

17. Which is the correct relation for the given data?

A. IE₁ < IE₂ ≪ IE₃

B. IE₁ > IE₂ > IE₃

C. IE₁ = IE₂ = IE₃

D. IE₃ < IE₂

Answer: A

18. Which group usually forms M²⁺ ions readily?

A. Group 1

B. Group 2

C. Group 17

D. Group 18

Answer: B

19. The large IE₃ in this question indicates that M²⁺ is:

A. Relatively stable

B. Highly unstable

C. Neutral

D. An anion

Answer: A

20. Which element has the outer configuration ns²?

A. Group 1

B. Group 2

C. Group 17

D. Group 18

Answer: B

21. If IE₁ = 500, IE₂ = 1000 and IE₃ = 8000, the element most likely belongs to:

A. Group 1

B. Group 2

C. Group 13

D. Group 14

Answer: B

22. If the big jump occurs between IE₅ and IE₆, number of valence electrons is:

A. 4

B. 5

C. 6

D. 7

Answer: B. 5

23. Which is the most useful observation in this type of question?

A. Absolute value of IE₁

B. Largest relative jump

C. Atomic mass

D. Melting point

Answer: B

24. The number of relatively easy ionizations before the huge jump represents:

A. Number of neutrons

B. Number of valence electrons

C. Atomic mass

D. Number of shells only

Answer: B

25. Which Group 2 element has configuration [Ar]4s²?

A. Mg

B. Ca

C. Sr

D. Ba

Answer: B. Ca

26. Which element has two electrons in its outermost shell?

A. Be

B. B

C. C

D. N

Answer: A. Be

27. The big jump after IE₂ means the third electron is:

A. Farther from nucleus

B. From an inner shell

C. A valence electron

D. A free electron

Answer: B

28. Which element is expected to have a large jump after IE₂?

A. Na

B. Mg

C. Al

D. Si

Answer: B. Mg

29. The given element most likely forms an ion with charge:

A. +1

B. +2

C. +3

D. −2

Answer: B. +2

30. The best conclusion from IE₁ = 735, IE₂ = 1445, IE₃ = 7730 is:

A. One valence electron → Group 1

B. Two valence electrons → Group 2

C. Three valence electrons → Group 13

D. Four valence electrons → Group 14

Answer: B. Group 2

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