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प्रश्न
In the modern periodic table, the positions of 1 to 20 elements are shown here. Identify the elements A and B. Write their atomic number.
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उत्तर
- Element A is lithium (Li).
Element B is neon (Ne). - Atomic number of element A is 3.
Atomic number of element B is 10.
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संबंधित प्रश्न
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.
What is the significance of atomic number in the modern classification of elements? Explain with the help of an example.
Consider the following elements:
Na, Ca, Al, K, Mg, Li
Which of these elements belong to the same group of the periodic table?
Give alongside is a part of the periodic table :
As we move horizontally from left to right:
| Li | Be | B | C | N | O | F | |
| Na | Mg | Al | Si | P | S | Cl |
(i) What happens to the metallic character of the elements?
(ii) What happens to the atomic size?
How does the chemical reactivity of alkali metals vary on going in group 1 of the periodic table?
What is the number of valence electrons in the atoms of first elements in a period?
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.
On the basis of electronic configuration, how will you identify the first element of a period?
What are the groups in a periodic table? Give two characteristics of each.
Which of the following are the correct characteristics of isotopes of an element?
(i) same atomic mass
(ii) same atomic number
(iii) same physical properties
(iv) same chemical properties
(a) (i), (ii) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
The atomic numbers of the three elements X, Y and Z are 2, 6 and 10 respectively.
(i) Which two elements belong to the same group?
(ii) Which two elements belong to the same period?
Give reasons for your choice.
Give the group number of following elements present in periodic table
Name the scientist who stated the modern periodic law.
How many groups and periods does the modern periodic table have?
Answer the following in respect of element `31/15 P `
To which group and period does it belong?
Answer the following in respect of element `31/15 P`
Give its electronic configuration
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 period number of T?
State the main aim of classifying elements. Which is the more fundamental property of elements that is used in the development of Modern Periodic Table? Name and state the law based on this fundamental property. On which side of the periodic table one can find metals, non-metals and metalloids?
Name an element of group 18 which can form compounds.
Give the symbol and valency of the following element and radical.
Sodium
Give the symbol and valency of the following element and radical.
Oxygen [Oxide]
Give the symbol and valency of the following element and radical.
Nitrate
Give the symbol and valency of the following element and radical.
Bisulphate
Give the symbol and valency of the following element and radical.
Hydroxide
The groups 1 and 2 constitute the _______ block.
Find the odd one out and give its explanation.
The modern periodic table is divided into which blocks?
To the left of the zig-zag line in the periodic table are the metal elements.
Distinguish between:
Group 17 - Group 18
Explain structure of modern periodic table in short.
Elements in the modern periodic table are arranged in ______groups and______ periods.
What are groups and periods in the modern periodic table?
______ and ______ are called inner transition elements.
Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?
Name the metalloids in the first twenty elements.
