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प्रश्न
Write a scientific reason.
There was ambiguity about the correct position of hydrogen in Mendeleev’s periodic table.
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उत्तर
- Hydrogen resembles alkali metals. It has one electron in its outermost shell like alkali metals. Its valency is 1 like alkali metals. It forms oxides (H2O) similar to alkali metals (Na2O). However, hydrogen also resembles halogens. It is a diatomic molecule (H2) like halogens (F2, Cl2). It is one electron deficient to achieve stable electronic configuration similar to halogens.
- Due to this unique behaviour of hydrogen, it could not be decided whether the correct position of hydrogen is in the group of alkali metals or in the group of halogens.
Thus, there was ambiguity about the correct position of hydrogen in Mendeleev's periodic table.
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संबंधित प्रश्न
Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
The position of three elements A, B and C in the Periodic Table are shown below –
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Group 16
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Group 17
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A
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B
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C
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(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
How does the metallic character of elements in Modern Periodic Table vary on moving from left to right in a period, and (ii) down a group?Give reason to justify your answer.
State modern periodic law.
What is meant by a group, in a periodic table?
Name the scientist who prepared modern periodic table.
The three elements having chemical symbols of Si, B and Ge are:
(a) all metals
(b) all non-metals
(c) all metalloids
(d) Si is metalloid, B is metal and Ge is non-metal
The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of elements is:
(a) electron
(b) proton
(c) neutron
(d) meson
What is the major characteristic of the first elements in the periods of the periodic table? What is the general name of such elements?
Explain why all the elements of a group have similar chemical properties.
What is a group in the periodic table?
What are the advantages of the periodic table?
An element X belongs to 3rd period and group 2 of the periodic table. State:
(a) number of valence electrons
(b) valency
(c) metal or non-metal
(d) name of the element
How many groups and periods does the modern periodic table have?
Name two elements in halogens.
Name two elements in each case:
Transition element
Name two elements in each case: Lanthanides
What do you understand by typical elements?
Name the type of elements which have two outermost shell incomplete.
State its position in the periodic table?
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What is the group number of T?
State the modern periodic law.
What is the number of elements in the 3rd period, of the modern periodic table?
An element A has 2 electrons in its fourth shell. State its electronic configuration.
Give the symbol and valency of the following element and radical.
Aluminium
Give the symbol and valency of the following element and radical.
Nitrogen [Nitride]
Give the symbol and valency of the following element and radical.
Nitrate
Give the chemical formula of sodium nitrate
Give the chemical formula of magnesium nitrate
Give the chemical formula of calcium phosphate
Noble gases belong to______ group of the periodic table.
State whether true or false. If false, correct the statement.
Lanthanides and actinides are kept at the bottom of the periodic table because they resemble each other but they do not resemble with any other group elements.
Which of the following elements would lose an electron easily?
The maximum number of electrons that can be accommodated in s, p,d, and f subshells are ______.
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Answer the following in respect of element \[\ce{_16^32S}\].
To which group and period does it belong?
Match the atomic number with the following:
An element of group 2.
