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Question
An element A has 2 electrons in its fourth shell. State:
its valency
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Solution
Its valency is 2.
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RELATED QUESTIONS
Given below are some elements of the modern periodic table. Atomic number of the element is given in parentheses.
A(4), B(9), C(14), D(19), E(20)
(a) Select the element that has one electron in the outermost shell. Also, write the electronic configuration of this element.
(b) Which two elements amongst these belong to the same group? Give reasons for your answer.
(c) Which two elements amongst these belong to the same period? Which one of the two has bigger atomic radius?
Study the following table in which positions of six elements A, B, C, D, E and F are shown as they are in the modern periodic table:
|
Group→
Period↓ |
1
|
2
|
3-12
|
13
|
14
|
15
|
16
|
17
|
18
|
| 2 | A | B | C | ||||||
| 3 | D | E | F |
On the basis of the above table, answer the following questions:-
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of D and E, which is bigger in size and why?
(v) Write the common name for the family to which the elements C and F belong.
Fill in the blank in the following statement:
The tendency to gain an electron ............... on moving down in a group of the periodic table.
How does Chemical reactivity of elements change on going from left to right in a period of the periodic table?
Give example in support of your answer.
The elements A, B, C, D and E have atomic numbers 9, 11, 17, 12 and 13 respectively. The pair of elements which belongs to the same group of the periodic table is:
(a) A and B
(b) B and D
(c) A and C
(d) D and E
Which one of the following does not increase while moving down the group of the periodic table?
State the trends in physical properties on moving down the group. Give an example to illustrate.
F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each.
On the basis of electronic configuration, how will you identify the first and the last element of a period?
There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively.
Classify the above elements as metals and non-metals.
