Explain the deviation in ionization enthalpy of some elements from the general trend by using the given figure.
Ionisation enthalpy increases in a period with increase in atomic number. The graph shows few exceptions and not the linear relationship. Ionisation enthalpy of Be is greater than that of B due to filled s-orbital in Be (Be – l.s2 1s2, B – 1s2 2s2 2pl).
Ionisation enthalpy of N is greater than that of O due to half-filled/?-orbitals in nitrogen.
(N – Is2 2s 22p3 O – ls 2 2s2 2p4).
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
Discuss the main characteristics of four blocks of elements in the periodic table? Give their general electronic configuration.
What is the basic difference in approach between Mendeleev’s Periodic Law and the Modem Periodic Law?
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?
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Show by a chemical reaction with water that Na20 is a basic oxide and Cl207 is an acidic oxide.
Consider the isoelectronic species, Na+, Mg2+, F and O2-. The correct order of increasing length of their radii is
How do atomic radius vary in a period and in a group? How do you explain the variation?
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?
Discuss the main features of long form of the periodic table. What are the advantages of long . form of 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
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
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.
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
Illustrate by taking examples of transition elements and non-transition elements that oxidation states of elements are largely based on electronic configuration.
What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.
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?
Would you expect the second electron gain enthalpy of O as positive, more negative or less negative than the first? Justify your answer.
Electronic configurations of four elements A, B, C and D are given below:
(A) 1s2 2s12p6
(B) 1 s2 2s2 2p4
(C) 1s2 2s2 2p6 3s1
(D) Is2 2s2 2p5
Which of the following is the correct order of increasing tendency to gain electron?
(a) A < C < B < D
(b) A < B < C < D
(c) D < B < C < A
(d) D < A< B < C
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.
Explain the following:
(a) Electronegativity of elements increases on moving from left to right in the periodic table.
(b) Ionisation enthalpy decreases in a group from top to bottom.
Which important property did Mendeleev use to classify the elements in this periodic table and did he stick to that?
Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
What do you understand by isoelectronic species? Name a species that tvill be iso electronic with each of the following atoms or ions.
(i) F–(ii) Ar (iii) Mg2+(iv) Rb+
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 are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down the group?
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?
What is basic difference between the terms electron gain enthalpy and electro negativity?
The increasing order of reactivity among group 1 elements is Li < Na < K < Rb < Cs whereas that of group 17 is F > Cl > Br > I. Explain?
Explain why chlorine can be converted into chloride ion more easily as compared to fluoride ion from fluorine ?
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.
