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प्रश्न
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उत्तर
Atomic size increases down the group
- The atomic numbers of the elements increase as we go down the group. Thus, the elements placed lower have more electrons.
- To accommodate these electrons new shells are added to the atom.
- These new shells take the outermost electrons farther from the nucleus causing atomic size (radius) to increase as we go down the group.
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संबंधित प्रश्न
From the following elements :
4Be; 9F; 19K; 20Ca
(i) Select the element having one electron is the outermost shell.
(ii) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2, 8, 7).
Write the number of periods the Modern Periodic Table has. State the changes in valency and metallic character of elements as we move from left to right in a period. Also state the changes, if any, in the valency and atomic size of elements as we move down a group.
List any two properties of the elements belonging to the first group of the modern periodic table.
Define the term : Valency
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
The metal of Group 2 from top to bottom arc Be, Mg, Ca, Sr, and Ba.
1) Which one of these elements will form ions most readily and why?
2) State the common feature in the electronic configuration of all these elements.
What happens to the metallic character of the elements as we go down in a group of the periodic table?
How does the number of valence electrons vary on moving from left or right in the second period of the periodic table?
How does the valency of elements vary in going down a group of the periodic table?
Rewrite the following statement after correction, if necessary:
The metallic character of elements in a period increases gradually on moving from left to right.
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?
Why does the size of the atoms progressively become smaller when we move from sodium (Na) to chlorine (Cl) in the third period of the periodic table?
The atomic number of an element is 20. In modern periodic table, this element is placed:
(a) 2nd period
(b) 4th period
(c) 3rd period
(d) 1st period
Given alongside is a part of the periodic table. As we move vertically downward from Li to Fr:
| Li | Be |
| Na | |
| K | |
| Rb | |
| Cs | |
| Fr | Ra |
What happens to their metallic character?
Which of the following set of elements is written correctly in the order of their increasing metallic character?
(a) Mg, Al, Si
(b) C, O, N
(c) Na, Li, K
(d) Be, Mg, Ca
An element X belong to 4th period and 17th group, state.
no of valence electrons in it
An element X belong to 4th period and 17th group, state.
name of the element.
An element X belong to 4th period and 17th group, state.
name the family to which it belong.
An element barium has atomic number 56. Look up its position in the periodic table and answer the following question.
Is it more or less reactive than calcium?
Complete the following sentences.
The properties of the elements are a periodic function of their …………… (atomic number, mass number, reative atomic mass).
Name the non-metals present in period 2 and metals in period 3.
What is the common feature of the electronic configuration of the elements at the end of period 2, and period 3?
Calculate the valency of element X whose atomic number is 9.
Select the correct answer
Most reactive character among the elements given below is found in
How many elements are there in period 2?
The following table represents the first period of the modern periodic table. Study the table and answer the questions that follow:
- Write the formula of the sulphate of the element with atomic number 13.
- What type of bonding will be present in the oxide of the element with atomic number 1?
- Which feature of the atomic structure accounts for the similarities in the chemical properties of the elements in group VIIA of the periodic table?
- Name the element which has the highest ionization potential.
- How many electrons are present in the valence shell of the element with atomic number 18?
- What is the name given to the energy released, when an atom in its isolated gaseous state accepts an electron to form an anion?
- What is the electronic configuration of the element in the third period which gains one electron to become an anion?
- Fill in the blanks:
The atomic size ______ as we move from left to right across the period, because the ______ increases, but the ______ remains the same.
Arrange the following as per instruction given in the bracket.
Mg, Cl, Na, S, Si (decreasing order of atomic size)
Arrange the following as per instruction given in the bracket.
Cs, Na, Li, K, Rb (increasing metallic character)
Arrange the following as per instruction given in the bracket.
Li, K, Na, H ( decreasing order of their potential ionisation )
Choose the word or phrase from the bracket which correctly complete each of the following statement:
Metals are good ................. (oxidising agents/reducing agents) because they are electron ............. (acceptors/donors).
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 |
Which type of ion will be formed by elements A, B, and C.
Write the electronic configuration of element 17T35.
- What is the group number of T?
- What is the period number of T?
- How many valence electrons are there in an atom of T?
- What is the valency of T?
- Is it a metal or non-metal?
- State number of protons and neutrons in T.
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the number of valence electrons,
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 period which is the shortest period of the periodic table.
Name the elements in the correct order of their increasing atomic numbers present in the first, second, and third short periods of the periodic table.
State which of the elements are –
- metallic
- non-metallic
- noble gases
in each of the periods 2 and 3.
