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Question
Name and state the following with reference to the elements of the first three periods of the periodic table.
Valency of elements in Group 14 and 15.
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Solution
4, 3
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RELATED QUESTIONS
The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis.
| Period No. | ||
| 2 | Li(3) | Be(4) |
| 3 | Na(11) | Mg(12) |
| 4 | K(19) | Ca(20) |
| 5 | Rb(37) | Sr(38) |
(i) Write the electronic configuration of Ca.
(ii) Predict the number of valence electrons in Rb.
(iii) What is the number of shells in Sr?
(iv) Predict whether K is a metal or a non – metal.
(v) Which one of these elements has the largest atom in size?
(vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms.
Rewrite the following statement after correction, if necessary:
The metallic character of elements in a period increases gradually on moving from left to right.
In terms of electronic configurations, explain the variation in the size of the atoms of the elements belonging to the same period and same group ?
An element X belong to 3rd periods and group II of the periodic table state:
the valency,
In the following table, the positions of six elements A, B, C, D, E and F are given as they are in the Modern Periodic Table :
 |
1 | 2 | 3-12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 2 | A | B | C | D | |||||
| 3 | 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 B and C, whose atomic radius is bigger and why ?
(v) Write the common name for the family to which the elements D and F belong.
What will be the valency of an element of atomic number 9 (nine)?
On the basis of electronic configuration, how will you identify the first and the last element of a period?
Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element. 
Which is an inert gas?
How many elements are there in period 2?
The electronic configuration of an element is 2, 8, 4. State it:
group and period in the Modern Periodic Table.
