Among the second period elements, the actual ionization enthalpies are in the order: Li
(i) Be has higher ∆iH1than B ?
(ii) O has lower ∆iH1 than N and F?
(i) In case of Be (1s2 2s2) the outermost electron is present in 2s-orbital while in B (1s2 2s2 2p1) it is present in 2p-orbital. Since 2s – electrons are more strongly attracted by the nucleus than 2p-electrons, therefore, lesser amount of energy is required to knock out a 2p-electron than a 2s – electron. Consequently, At of Be is higher than that ∆iH1 of B.
(ii) The electronic configuration of
N7 = 1s2 2s2 2px1 2py1 2pz1
O8 =1s2 2s2 2px1 2py1 2pz1
We can see that in case of nitrogen 2p-orbitals are exactly half filled. Therefore, it is difficult to remove an electron from N than from O. As a result ∆iH1 of N is higher than that of O.
Give reasons:
(i) IE1 of sodium is lower than that of magnesium whereas IE2 of sodium is higher than that of magnesium.
(ii) Noble gases have positive value of electron gain enthalpy.
All transition elements are d-block elements, but all d-block elements are not transition elements. Explain.
Discuss the main characteristics of four blocks of elements in the periodic table? Give their general electronic configuration.
Would you expect the first ionization enthalpies of two isotopes of the same element to be the same or different? Justify your answer.
The electronic configuration of an element is Is 2s 2p 3s 3p 4s . Locate the element in the periodic table.
Energy of an electron in the ground state of the hydrogen atom is- 2.18 x 10-18 J.Calculate the ionization enthalpy of atomic hydrogen in terms of JMol-1.[Hint: Apply the idea of mole concept to derive the answer],
Name different blocks of elements in the periodic table. Give general electronic configuration of each block.
Use periodic table to answer the following questions:
(a) Identify the element with five electrons in the outer subshell.
(b) Identify the element that would tend to lose two electrons.
(c) Identify the element that would tend to gain two electrons.
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)?
Show by a chemical reaction with water that Na20 is a basic oxide and Cl207 is an acidic oxide.
Which of the following elements can show covalency greater than 4?
(a) Be (b) P (c) S (d) B
Which of the following have no unit?
(a) Electronegativity (b) Electron gain enthalpy
(c) Ionisation enthalpy (d) Metallic character
Arrange the elements N, P, O and S in the order of
(i) increasing first ionisation enthalpy.
(ii) increasing non-metallic character.
Give reason for the arrangement assigned.
Discuss and compare the trend in ionization enthalpy of the elements of group 1 with those of group 17 elements.
What is the cause of periodicity in properties of the elements? Explain with two examples.
Which of the following sequences contain atomic numbers of only representative elements?
(a) 3, 33, 53, 87
(b) 2, 10, 22, 36
(c) 7, 17,25,37,48
(d) 9,35,51,88
The first ionization enthalpy values (in kJ mol -1) of group 13 elements are:
B Al Ga In Tl
801 577 579 558 589
How would you explain this deviation from the general trend?
Would you expect the second electron gain enthalpy of O as positive, more negative or less negative than the first? Justify your answer.
Define the term ionization enthalpy? How does it vary along a period and along a group?
An element belongs to 3rd period and group-13 of the periodic table. Which of the following properties will be shown by the element?
(a) Good conductor of electricity
(b) Liquid, metallic
(c) Solid, metallic
(d) Solid, non metallic
How do atomic radius vary in a period and in a group? How do you explain the variation?
Consider the following species:
N3-, O2-, F–, Na+, Mg2+, Al3+
(a) What is common in them?
(b) Arrange them in order of increasing ionic radii?
Among the second period elements, the actual ionization enthalpies are in the order: Li
(i) Be has higher ∆iH1than B ?
(ii) O has lower ∆iH1 than N and F?
In which of the following options order of arrangement does not agree with the variation of property indicated against it?
(a) Al3+ < Mg2+ < Na+ < F– (increasing ionic size)
(b) B < C < N < O (increasing first ionization enthalpy)
(c) I < Br < Cl < F (increasing electron gain enthalpy)
(d) Li < Na < K < Rb (increasing metallic radius)
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 |
Justify the given statement with suitable examples "the properties of the elements are a periodic function of their atomic numbers".
What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down the group?
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
Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidising property is:
(a) F > Cl> O > N (b) F > O > Cl> N (c) Cl> F > O > N (d) O > F > N > Cl
Discuss the factors that influence the magnitude of ionization enthalpy. What are the general trends of variation of ionization enthalpy in the periodic table? Explain.
(a) How does atomic radius vary in group in the periodic table?
(b) Explain
(i) Radius of cation is less than that of the atom.
(ii) Radius of anion is more than that of the atom.
(iii) In iso-electronic ion, the ionic radii decreases with increase in atomic number.
Consider the isoelectronic species, Na+, Mg2+, F and O2-. The correct order of increasing length of their radii is
First member of each group of representative elements (i.e., s and p-block elements) shows anomalous behaviour. Illustrate with two examples.
p-Block elements form acidic, basic and amphoteric oxides. Explain each property by giving two examples and also write the reactions of these oxides with water.
Explain the deviation in ionization enthalpy of some elements from the general trend by using the given figure.
Electronic configurations of some elements are given in column I and their electron gain enthalpies are given in column II. Match the electronic configuration with electron gain enthalpy.
|
Column I (Electronic configuration) |
Column II ' (Electron gain enthalpy/kJ moL-1 |
| (i) 1s2 2s2 2p6 | A. -53 |
| (ii) ls22s22p63sl | B. -328 |
| (iii) ls22s22p5 | C. -141 |
| (iv) 1s2 2S2 2p4 | D. +48 |
Discuss the factors affecting electron gain enthalpy and the trend in its variation in the periodic table.
