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प्रश्न
Explain, the statement 'In each period, the atomic radii gradually decrease with increase in atomic number'. Give one example to justify your answer.
उत्तर
The statement that in each period, the atomic size gradually decreases with increase in atomic number means that as move from left to right in a period, nuclear charge increases by one unit in each succeeding element while the number of shells remains the same. Due to this increased nuclear charge, the electrons of all the shells are pulled closer to the nucleus thereby bringing the outer most shell closer to the nucleus. With the result, the atomic size decreases across a period.
For example, in the second period from lithium to fluorine, lithium has the largest size while fluorine has the smallest size.
| Element | Li | Be | B | C | N | O | F |
| Atomic number | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| Atomic radius (A°) | 1.23 | 0.90 | 0.80 | 0.77 | 0.75 | 0.74 | 0.72 |
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संबंधित प्रश्न
The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons in the outermost shell respectively. State the period in which these elements can be placed in the modern periodic table. Write the electronic configuration of the atoms of A and D and the molecular formula of the compound formed when A and D combine.
The metal of Group 2 from top to bottom arc Be, Mg, Ca, Sr, and Ba.
1) Which one of these elements will form ions most readily and why?
2) State the common feature in the electronic configuration of all these elements.
An element 'M' has atomic number 12.
(a) Write its electronic configuration.
(b) State the group to which 'M' belongs.
(c) Is 'M' a metal or a non-metal.
(d) Write the formula of its chloride.
What is meant by a group in the periodic table?
Arrange the following as per instruction given in the bracket.
Cl, F, Br, I (increasing electron affinity)
The elements of one short period of the periodic table are given below in order from left to right:
| Li | Be | B | C | O | F | Ne |
To which period do these elements belong?
Write the electronic configuration of element 17T35.
- What is the group number of T?
- What is the period number of T?
- How many valence electrons are there in an atom of T?
- What is the valency of T?
- Is it a metal or non-metal?
- State number of protons and neutrons in T.
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the name of the element.
An element A has 2 electrons in its fourth shell. State:
is it an oxidising or reducing agent
Name or state following with reference to the element of the first three periods of the periodic table.
The valency of elements in group 1 [I–A].
