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Classification Of Elements And Periodicity In Properties

Question
CBSEENCH11005498
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Why is ionisation enthalpy of Be more than that of B?

Solution

The electronic configuration of Be (Z = 4) and B(Z = 5) are,

(i) The electronic configuration of Be in which all the occupied orbitals are fully filled is more stable than boron.
(ii) It is relatively easier to remove electron from 2p subshell in boron than removal of electrons from 2s subshell in Be as 2p orbital is less penetrating than 2s orbital. Therefore, 2p electron of B is less firmly held by the nucleus and so, it is relatively easily removed.

Some More Questions From Classification of Elements and Periodicity in Properties Chapter

What is the number of groups in: (i) p-block  (ii) d-block?

How many elements are present in:
(i) second period    
(ii) fourth period    
(iii) sixth period?

What is the name given to the s-block elements?

To which block the element with outer electronic configuration 4s23d10 belongs?

Why are there 10 elements in each series of d-block?

In terms of electronic configuration,
what is common in a given period and group?

Give the general electronic configuration of
(i) Transition elements     (ii) Inner transition elements.

Name the group and period to which an element with Z = 15 belongs ?

What are the advantages of periodic classification of elements?

In the modern periodic table, the period indicates the value of:
(a) atomic number
(b) atomic mass
(c) principal quantum number
(d) azimuthal quantum number.

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