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प्रश्न
Write scientific reason.
Lithium and sodium are included in the same group in periodic table.
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उत्तर
- Electronic configuration of lithium is (2, 1). Electronic configuration of sodium is (2, 8, 1).
- Both lithium and sodium have single electron in their outermost shell.
- Their valency is 1.
- In the periodic table, elements belonging to the same group have the same valency. Hence, lithium and sodium are included in the same group in periodic table.
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संबंधित प्रश्न
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
What is periodicity in properties of elements with reference to the Modern Periodic Table?
How does the tendency of elements to gain electrons change as we move from left to right in a period? State the reason of this change.
What is meant by a group, in a periodic table?
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
State whether the following statement is true or false:
On going down in a group of the periodic table, the number of valence electrons increases.
What is the main characteristic of the last elements in the periods of the periodic table? What is the general name of such elements?
What is the number of elements is 1st period the modern periodic table?
The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers. (The letters given here not the chemical symbols of the elements):
| a 3 |
b 4 |
c 5 |
d 6 |
e 7 |
f 8 |
g 9 |
h 10 |
|
| i 11 |
j 12 |
k 13 |
l 14 |
m 15 |
n 16 |
o 17 |
p 18 |
(i) Which element has a bigger atom, a or f?
(ii) Which element has a higher valency, k or o?
(iii) Which element is more metallic i or k?
(iv) Which element is more non-metallic, d or g?
(v) Select a latter which represents a metal of valency 2.
(vi) Select a letter which represents a non-metal of valency 2.
Correct the statement.
Transition elements are placed at extreme right of the periodic table.
Name two elements in Alkaline earth metals.
Name the type of elements which have two electrons in the outermost orbit.
An element barium has the atomic number 56. Look up its position in the periodic table and answer the following question.
Is it larger or smaller than caesium (Cs)?
The electronic configuration of an element T is 2, 8, 8, 1.
What is the group number of T?
State the modern periodic law.
Name and state the following with reference to the elements of the first three periods of the periodic table.
A covalent compound formed by an element in period 2 and a halogen.
Name the cation and the anion in the salt – calcium sulphate
Give the symbol and valency of the following element and radical.
Potassium
Give the symbol and valency of the following element and radical.
Zinc
Give the symbol and valency of the following element and radical.
Bicarbonate
Give the symbol and valency of the following element and radical.
Bisulphite
Give the symbol and valency of the following element and radical.
Hydroxide
Give the chemical formula of sodium hydroxide
What are the elements.
Group 1 and 2 : s block : : group 13 and 18 : _______
Group 13 to 18 : p block : : _______ : d block
The modern periodic table shows the molecular masses of the elements in each frame.
p-block is composed of groups 1 and 2.
To the left of the zig-zag line in the periodic table are the metal elements.
The K and L shells of the elements Na and Mg contain electrons.
An X element with atomic number 11 and Y element with atomic number 13 belongs to the third period in the modern periodic table. With this information, give the answers of the below questions.
- Which element has more metallic character from these two elements?
- What is the valency of each X and Y elements?
- Atom size of Y element is smaller than atom size of X element. Explain.
What is the symbol of the element Tungsten?
Which of the following elements does not lose an electron easily?
Compare the radii of two species X and Y. Give reasons for your answer.
- X has 12 protons and 12 electrons
- Y has 12 protons and 10 electrons
A part of modern periodic table is given below. On its basis, answer the following questions:
| Group No. → | 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 |
| Period ↓ | ||||||||
| 2 | A | B | ||||||
| 3 | E | D | F | C |
Which of the element is a Noble gas?
An element belonging to 3d series of modern periodic table has spin magnetic moment = 5.92 B.M. in +3 oxidation state. The atomic number of elements are ______.
An element has 2 electrons in its N shell.
Is it a metal or a non-metal?
A group of elements in the periodic table is given below (Boron is the first member of the group and Thallium is the last).
Boron, Aluminium, Gallium, Indium, Thallium
Answer the following question in relation to the above group of elements:
If the electronic configuration of aluminium is 2, 8, 3, how many electrons are there in the outer shell of thallium?
