1. An element has electronic configuration 2, 8, 3. What is the atomic number of this element? To which (i) group and (ii) period this element belong?
2. State the positions of (i) isotopes of the same element and (ii) hydrogen in the Modern Periodic Table.
3. How does the tendency to gain electrons change as we go down the 16th group of periodic table? Why?
4. Give reasons for the following : (a) Lithium atom is smaller than sodium atom. (b) Chlorine (atomicnumber 17) is more electronegative than sulphur (atomic number 16)
5. (a) State the Modern Periodic Law. (b) Name the element which has twice as many electrons in its second shell as in its first shell. Write its electronic configuration also.
3 Marks Questions [ 3 x 5 = 15 ]
1. An element X belongs to group 17 and third period of the periodic table. (a) Write electronicconfiguration of the element. What is its valency? (b) Predict its nature, whether it is a metal or non-metal. (c) Give the formula of the compound formed when it combines with an element Y having valency three.
2. Three elements A, B and C have atomic number 7, 8 and 9 respectively. (a) What would be their positions in the Modern Periodic Table (Mention group and period both)? (b) Arrange A, B and C in the decreasing order of their size. (c) Which one of the three elements is most reactive and why?
3. (a) The elements of the second period along with their atomic number in parenthesis are given below : B (5), Be (4), O (8), N (7), Li (3), C (6), F (9) (i) Arrange them in the same order as they are in the periodic table. (ii) Which element has the (i) largest (ii) smallest atom? (b) Why does the atomic radius change as we move from left to right in a period?
4. (a) How is the valency of an element determined from its position in the periodic table? (b) Magnesium has atomic number 12. To which (i) group (ii) period of the periodic table does it belong? (c) The valency of all the elements in a group is same. Why?
5. A part of the periodic table has been shown below :
Group →
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1
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2
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13
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14
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15
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16
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17
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18
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Period ↓
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1
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2
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A
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C
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E
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G
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3
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B
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D
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F
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Answer the following questions on the basis of position of elements in the above table.
(a) Which element is a noble gas? Give reason.
(b) Which element is most electronegative? Give reason.
(c) Write the electronic configuration of (i) B and (ii) E.
5 Marks Questions [ 5 x 1 = 5]
1. What are electron affinity and ionization energy? How they are vary in group and periods in modern periodic table? OR, Two elements ‘A’ and ‘B’ belong to group 1 and 2 respectively in the same period. Compare them with respect to :– (a) Number of valence electrons (b) Valency (c) Metallic character (d) Size of atom (e) Formulae of their oxides.
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