Long Answer TypeA, B, C are three elements, B is an inert gas element other than helium; with this information, complete the table given below:
| Element | Atomic No. | No. of electrons in the valence shell | Group to which element belongs |
| A | Z - 1 | ||
| B | Z | ||
| C | Z+1 |
Also, explain the following:
(i) Electron gain enthalpy of element A has large negative value than that of C.
(ii) Ionisation enthalpy of element C is less than that of A.
(iii) Electron gain enthalpy of B is positive.
Let B be an inert gas element neon with atomic number Z=10. Therefore, atomic number of A=9 (halogen) and of C=11 (alkali metal).
The electronic configuration of elements are:
Groups:
Element A belongs to Group 17 (Halogens).
Element B belongs to Group 18 (Noble gases).
Element C belongs to Group 11 (Alkali metals).
(i) Electron gain enthalpy of element A has large negative value than that of C. The element A (fluorine) requires only one electron to have a noble gas configuration. Thus, electron gain enthalpy of A is much more than that of C (sodium).
(ii) Ionisation enthalpy of C is less than that of A. The atomic size of A is smaller (atomic radius = 71 pm) than that of C (atomic radius = 154 pm).Thus, it is easier to remove an electron from C as compared to A. Hence ionisation enthalpy of C is less than that of B.
(iii) Electron gain enthalpy of B is positive. B being a noble gas element has a symmetrical electronic configuration ( 1s-2s22p6). Added electron has to enter the next higher principal quantum level leading to the positive value of electron gain enthalpy.
Define electronegativity. Explain the factors influencing electronegativity. How does it vary along periods and groups? what are its units?
Short Answer TypeExplain giving various reasons for the variation of electronegativity along a period and along a group.
Long Answer TypeWhat is the basic difference between the terms electronegativity and electron gain enthalpy?
Short Answer TypeHow would you react to the statement that the electronegativity of N on Pauling scale is 3.0 in all the nitrogen compounds?
Long Answer TypeThe valence of representative elements is either equal to the number of valence electrons or eight minus the number. What is the basis of their rule?
Short Answer TypePredict the formulae of the stable binary compounds that would be formed by the following pairs of elements:
silicon and oxygen
Predict the formulae of the stable binary compounds that would be formed by the following pairs of elements:
aluminium and bromine
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