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.
To match the correct enthalpy with the elements and to complete the graph, the following points are taken into consideration. As we move from left to right across a period, the ionization enthalpy keeps on increasing due to increased nuclear charge and simultaneous decrease in atomic radius. However, there are some exceptions given below- –
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.
What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down the group?
What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.
Which of the following elements can show covalency greater than 4?
(a) Be (b) P (c) S (d) B
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?
What do you understand by ‘Representative elements’? Name the groups whose elements are called representative elements.
Explain the deviation in ionization enthalpy of some elements from the general trend by using the given figure.
Discuss the main features of long form of the periodic table. What are the advantages of long . form of periodic table?
The first ionisation enthalpy of magnesium is higher than that of sodium. On the other hand, the second ionisation enthalpy of sodium is very much higher than that of magnesium. Explain.
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
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.
Consider the isoelectronic species, Na+, Mg2+, F and O2-. The correct order of increasing length of their radii is
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?
Predict the formulas of the stable binary compounds that would be formed by the combination of the following pairs of elements:
(a) Lithium and oxygen(b) Magnesium and nitrogen
(c) Aluminium and iodine(d) Silicon and oxygen
(e) Phosphorous pentafluoride (f) Element 71 and fluorine.
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?
Which of the following statements related to the modem periodic table is incorrect?
(a) The p-block has six columns, because a maximum of 6 electrons can occupy all the orbitals in a p-subshell.
(b) The d-block has 8 columns, because a maximum of 8 electrons can occupy all the orbitals in a d-subshell.
(c) Each block contains a number of columns equal to the number of electrons that can occupy that subshell.
(d) The block indicates value of azimuthal quantum number (l)for the last subshell that received electrons in building up the electronic configuration.
First member of each group of representative elements (i.e., s and p-block elements) shows anomalous behaviour. Illustrate with two examples.
What is basic difference between the terms electron gain enthalpy and electro negativity?
The electronic configuration of an element is Is 2s 2p 3s 3p 4s . Locate the element in the periodic table.
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.
Write down the outermost electronic configuration of alkali metals. How will you justify their placement in group 1 of the periodic table?
What is the basic difference in approach between Mendeleev’s Periodic Law and the Modem Periodic Law?
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Which element do you think would have been named by
(i)Lawrence Berkeley Laboratory
(ii)Seaborg’s group?
Which of the following pairs of elements would have a move negative electron gain enthalpy? (i) O or F (ii) F or Cl.
Explain why chlorine can be converted into chloride ion more easily as compared to fluoride ion from fluorine ?
Define the term ionization enthalpy? How does it vary along a period and along a group?
Give the electronic configuration of the transition elements. Write their four important characteristics.
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.
Which of the following sets contain only isoelectronic ions?
(a) Zn2+, Ca2+, Ga3+, Al3+
(b) K+, Ca2+, Sc3+, Cl–
(c) P3-, S2- Cl–,K+
(d) Ti4+, Ar, Cl3+, V5+
Which of the following have no unit?
(a) Electronegativity (b) Electron gain enthalpy
(c) Ionisation enthalpy (d) Metallic character
Explain why the electron gain enthalpy of fluorine is less negative than that of chlorine.
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 |
Discuss the factors affecting electron gain enthalpy and the trend in its variation in the periodic table.
Justify the given statement with suitable examples "the properties of the elements are a periodic function of their atomic numbers".