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प्रश्न
Name the elements in the correct order of their increasing atomic numbers present in the first, second, and third short periods of the periodic table.
State which of the elements are –
- metallic
- non-metallic
- noble gases
in each of the periods 2 and 3.
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उत्तर
Names of elements of:
| Period first | Hydrogen | Helium |
| H | He |
| Period – 2 | Li | Be | B | C | N | O | F | Ne |
| Lithium | Beryllium | Boron | Carbon | Nitrogen | Oxygen | Fluorine | Neon |
| Period – 3 | Na | Mg | Al | Si | P | S | Cl | Ar |
| Sodium | Magnesium | Alummium | Silicon | Phosphorus | Sulphur | Chlorine | Argo |
- Metals: Li, Be, Na, Mg, Al
- Non-metals: C, N, O, F, P, S, Cl
- Noble – gases: Ne, Ar
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संबंधित प्रश्न
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.
An element 'X' belong to 3rd period and group 13 of the Modern Periodic Table.
(a) Determine the valence electrons and the valency of 'X'.
(b) Molecular formula of the compound formed when 'X' reacts with an element 'Y' (atomic number = 8).
(c) Write the name and formula of the compound formed when 'X' combines with chlorine
An element 'X' has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'.
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
Why sodium element of group 1 and chlorine element of group 17 both have valency 1?
Why fluorine has higher E.N. than chorine?
Formula of ion of A is A2+. Element A probably belongs to ______ group.
An element A has 2 electrons in its fourth shell. State:
its valency
The electronic configuration of an element is 2, 8, 4. State it:
group and period in the Modern Periodic Table.
Electron Affinity is maximum in ______.
