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प्रश्न
Elements in the same group show the same valency. Give scientific reason.
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उत्तर
(a) The number of valence electrons in the outermost shell of an atom of an element is equal to the valency of an element.
(b) The number of valence electrons for all the elements in a group is the same. Therefore, the elements in the same group have the same valency.
(c) For example, the elements of Group I such as sodium (Na) and potassium (K) contain only one valence electron, and so, the valency of elements of Group I is one. Similarly, for Group II, the valency is two.
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संबंधित प्रश्न
Write the electronic configuration of K and Ne.
Two elements ‘P’ and ‘Q’ belong to the same period of the modern periodic table and are in Group 1 and Group 2, respectively. Compare their following characteristics in tabular form:-
(a) The number of electrons in their atoms
(b) The sizes of their atoms
(c) Their metallic character
(d) Their tendencies to lose electrons
(e) The formula of their oxides
(f) The formula of their chlorides
Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)
Match the atomic number 2, 4, 8, 15 and 19 with each of the following
1) A solid non metal belonging to the third period.
2) A metal of valency 1.
3) A gaseous element with valency 2.
4) An element belonging to Group 2
5) A rare gas.
Use the letters only written in the Periodic Table given below to answer the questions that Follow :
1) State the number of valence electrons in atom J.
2) Which element shown forms ions with a single negative charge?
3)Which metallic element is more reactive than R?
4) Which element has its electrons arranged in four shells?
The following table shows the electronic configuration of the elements W, X, Y, Z:
| Element | w | x | y | z |
| Electronic configurations |
2, 8, 1 | 2, 8, 7 | 2, 5 | 1 |
Answer the following questions based on the table above:
1) What type of Bond is formed between :
a) W and X
b) Y and Z
2) What is the formula of the compound formed between :
a) X and Z
b) W and X
Calculate the mass of Calcium that will contain the same number of the atom as are present in 3.2 gm of Sulphur.
[Atomic masses: S=32, Ca=40]
Differentiate between Normal elements and Transition elements.
Fill in the blank in the following statement:
The tendency to gain an electron ............... on moving down in a group of the periodic table.
How does the tendency to gain electrons change as we go down in group 17 of the periodic table? Why does it change this way?
In which part of a group would you separately expect the elements to have the largest atomic size?
Which of the following element does not lose an electron easily?
(a) Na
(b) F
(c) Mg
(d) Al
The correct increasing order of the atomic radii of the elements oxygen, fluorine and nitrogen is:
(a) O, F, N
(b) N, F, O
(c) O, N, F
(d) F, O, N
Correct the statements.
Elements in the same periods have equal valency.
What do you understand by orbits?
An element X belong to 4th period and 17th group, state.
Write the formula of the compound formed when it reacts with `(27)/(13) y `
Why fluorine has higher E.N. than chorine?
How do the following change on moving from left to right in a period of the periodic table?
Give examples in support of your answer.
atomic structure (electron arrangements) ?
Complete the following sentences
The similarities in the properties of a group of elements are because they have the same …………………
Name the non-metals present in period 2 and metals in period 3.
An element 'X' (Atomic number – 20) burns in the presence of oxygen to form a basic oxide.
(a) Identify the element and write its electronic configuration.
(b) State its group number and period number in the Modern Periodic Table.
(c) Write a balanced chemical equation for the reaction when this oxide is dissolved in water.
Atomic number of metal ‚A‛ is 11, while atomic number of metal ‚B‛ is 20. Which of them will be more reactive? Write the chemical reaction of dilute HCl with metal ‚A‛.
What is modern periodic law?
How many groups and periods are there in the modern periodic table?
Choose the most appropriate answer from the following list of oxides which fit the description.
An amphoteric oxide: Al2O3 (shows both acidic and basic properties)
Arrange the following as per the instruction given in the bracket
He,Ar,Ne (Increasing order of the number of electron shells)
The elements of one short period of the periodic table are given below in order from left to right:
| Li | Be | B | C | O | F | Ne |
One element of this period is missing. Which is the missing element and where should it be placed?
Formula of ion of A is A2+. Element A probably belongs to ______ group.
The position of elements A, B, C, D and E in the periodic table are shown below:
|
Group 1 |
Group 2 |
Group 17 |
Group 18 |
|
|
|
|
D |
|
|
B |
C |
|
|
A |
|
|
E |
State which is metals, non-metals, and noble gas in this table.
Element P has atomic number 19. To which group and period, does P belong? Is it a metal or a non-metal? Why?
Name and state the following with reference to the elements of the first three periods of the periodic table.
Non-metallic elements present in Period 3 of Groups 15 and 16.
An element A has 2 electrons in its fourth shell. State:
position in the periodic table
The electronic configuration of an element is 2, 8, 4. State it:
name and write its one physical property.
Write the electronic configuration of two elements A and B whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element A reacts with element B. State whether this compound is acidic, basic or neutral. Give a reason to justify your answer.
Name the elements in Period 1.
Name or state following with reference to the elements of the first three periods of the periodic table.
A metalloid in period 2 and in period 3.
State the following:
The group which contains highly electropositive metals including sodium.
