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प्रश्न
Write a scientific reason.
Lithium and sodium are included in the same group in the periodic table.
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उत्तर
- Electronic configuration of lithium is (2, 1). The 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 the periodic table.
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संबंधित प्रश्न
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?
State modern periodic law.
Is it possible to have an element having atomic number 1.5 placed between hydrogen and helium?
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
Which of the following statement about the modern periodic table is correct?
(a) It has 18 horizontal rows known as periods.
(b) It has 7 vertical columns known as periods.
(c) It has 18 vertical columns known as groups.
(d) It has 7 horizontal rows known as groups.
Consider the following elements:
Ca, Cl, Na, I, Li, Ba, Sr, K, Br
Separate these elements into three groups (families) of similar properties. State one property in each case on the basis of which you have made your choice.
How would the tendency to lose electrons change as we go from left to right across a period of the periodic table?
How does the chemical reactivity of the halogens vary on going in group 17 of the periodic table?
How do the atomic radii of elements change as we go from left to right in a period of the periodic table?
On the basis of electronic configuration, how will you identify the first element of a period?
Explain why, the first period of the periodic table has only two elements whereas second period has eight elements
Name two elements in Alkaline earth metals.
Name two elements in each case:
Transition element
Name the noble gas with 3 shells.
Give the symbol and valency of the following element and radical.
Nitrate
Give the chemical formula of sodium nitrate
Name the following:
The group of the Modern Periodic Table to which calcium [Ca2+] belongs.
State the number of elements in Period 1 of the Periodic Table.
State the number of elements in Period 2 of the Periodic Table.
State the number of elements in Period 3 of the Periodic Table.
Find the correlation:
Group 13 to 18 : p block : : ______ : d block
Complete the following flow chart.
Position of A, B and C three elements is given in the table from the modern periodic table. Answer the following questions.
| Periods | Group 2 | Group 17 |
| 2 | ----- | A |
| 3 | B | ----- |
| 4 | ----- | C |
- What is A element metal or nonmetal?
- Which is the outermost orbit of element B?
- Identify C element and it's physical state.
Explain structure of modern periodic table in short.
On moving from left to right in a period in the periodic table, the size of the atom ______
The amount of energy released when one or more electrons is added to the neutral atom is ______
Which of the following elements will form an acidic oxide?
Choose an element from period 3 of modern periodic table that matches the description given below in instance. Give a reason for your choice.
It has same valency as Lithium.
Choose an element from period 3 of modern periodic table that matches the description given below in instance. Give a reason for your choice.
It has variable valency and is a member of the Oxygen family (group 16).
Spot the error:
There are 5 periods and 17 groups in the modern periodic table.
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?
Explain giving reason why although the nuclear charge in atoms increases in moving from left to right in a period as well as in moving from top to bottom in a group in the Modern periodic table, but the size of the atoms does not vary similarly in both situations.
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:
A rare gas.
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?
