Which of the following pairs of elements would have a move negative electron gain enthalpy? (i) O or F (ii) F or Cl.
(i) O or F. Both O and F lie in 2nd period. As we move from O to F the atomic size decreases.
Due to smaller size of F nuclear charge increases.
Further, gain of one electron by
F —> F–
F~ ion has inert gas configuration, While the gain of one electron by
0->O–
gives CT ion which does not have stable inert gas configuration, consequently, the energy released is much higher in going from
F ->F–
than going from O >O–
In other words electron gain enthalpy of F is much more negative than that of oxygen.
(ii) The negative electron gain enthalpy of Cl (∆ eg H = – 349 kj mol-1) is more than that of F (∆ eg H = – 328 kJ mol -1).
The reason for the deviation is due to the smaller size of F. Due to its small size, the electron repulsions in the relatively compact 2p-subshell are comparatively large and hence the attraction for incoming electron is less as in the case of Cl.
Discuss the main characteristics of four blocks of elements in the periodic table? Give their general electronic configuration.
Ionisation enthalpies of elements of second period are given below:
Ionisation enthalpy/kJ mol-1: 520, 899, 801, 1086, 1402, 1314, 1681, 2080. Match the correct enthalpy with the elements and complete the graph given in figure. Also write symbols of elements with their atomic number.
Considering the elements B, Al, Mg and K, the correct order of their metallic character is:(a) B> Al> Mg > K(b) Al> Mg > B> K (c) Mg > Al> K> B (d) K> Mg > Al> B
How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?
Discuss the main features of long form of the periodic table. What are the advantages of long . form of periodic table?
What is the basic difference in approach between Mendeleev’s Periodic Law and the Modem Periodic Law?
Choose the correct order of atomic radii of fluorine and neon (in pm) out of the options given below and justify your answer.
(i) 72,160 (b) 160,160 (c) 72,72 (d) 160,72
Among the second period elements, the actual ionization enthalpies are in the order: Li
Explain why
(i) Be has higher ∆iH1than B ?
(ii) O has lower ∆iH1 than N and F?
Show by a chemical reaction with water that Na20 is a basic oxide and Cl207 is an acidic oxide.
Define electron gain enthalpy. What are its units? Discuss the factors which influence the electron gain enthalpy.
Consider the isoelectronic species, Na+, Mg2+, F and O2-. The correct order of increasing length of their radii is
Identify the group and valency of the element having atomic number 119. Also predict the outermost electronic configuration and write the general formula of its oxide.
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Assign the position of the element having outer electronic configuration,
(i) ns2 np4 for n = 3 (ii) (n – 1) d2 ns2 for n = 4 and (iii) (n – 2) f7 (n – 1) d1 ns2 for n = 6 in the periodic table?
Illustrate by taking examples of transition elements and non-transition elements that oxidation states of elements are largely based on electronic configuration.
Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
The first ionization enthalpies of Na, Mg, A1 and Si are in the order
(a) Na < Mg > A1 < Si
(b) Na>Mg>Al>Si
(c) Na < Mg < A1 < Si
(d) Na > Mg > A1 < Si
Among the elements B, Al, C and Si,
(a) which element has the highest first ionization enthalpy
(b) which element has the most metallic character?
Justify your answer in each case.
Would you expect the second electron gain enthalpy of O as positive, more negative or less negative than the first? Justify your answer.
Explain why chlorine can be converted into chloride ion more easily as compared to fluoride ion from fluorine ?
The electronic configuration of an element is Is 2s 2p 3s 3p 4s . Locate the element in the periodic table.
Those elements impart colour to the flame on heating in it, the atoms of which require low energy for the ionization (i.e., absorb energy in the visible region of spectrum). The elements of which of the following groups will impart colour to the flame?
(a) 2 (b) 13 (c) 1 (d) 17
First member of each group of representative elements (i.e., s and p-block elements) shows anomalous behaviour. Illustrate with two examples.
What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.
Match the correct atomic radius with the element.
Column I (Element) | Column II (Atomic radius (pm) |
Be | 74 |
C | 88 |
0 | 111 |
B | 77 |
N | 66 |
What is the significance of the terms – isolated gaseous atom and ground state while defining the ionization enthalpy and electron gain enthalpy?[Hint: Requirements for comparison purposes]
What is basic difference between the terms electron gain enthalpy and electro negativity?
How would you react to the statement that the electronegativity ofN on Pauling scale is 3.0 in all the nitrogen compounds?
Which of the above elements is likely to be:
(a) the least reactive element (b) the most reactive metal
(c) the most reactive non-metal (d) the least reactive non-metal
(e) the metal which can form a stable binary halide of the formula MX2(X = halogen)
(f) the metal which can form a predominantly stable covalent halide of the formula MX (X = halogen)?
In the modem periodic table, the period indicates the value of
(a)atomic number (b) mass number (c) principal quantum number (d) azimuthal quantum number?
Considering the elements B, C, N, F and Si, the correct order of their non-metallic character is: (a) B>C>Si>N>F (b) Si>C>B>N>F (c) F>N>C>B>Si (d) F>N>C>Si>B
What is the cause of periodicity in properties of the elements? Explain with two examples.
Name different blocks of elements in the periodic table. Give general electronic configuration of each block.
Elements A, B, C and D Iwoe atomic numbers 12,19, 29, and 36 respectively. On the basis of electronic configuration, write to which group of the periodic table each element belongs.