Advertisements
Advertisements
Question
Elements in the same group show the same valency. Give scientific reason.
Advertisements
Solution
(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.
APPEARS IN
RELATED QUESTIONS
Fill in the blank:
The formulae of chloride of metal M is MCl2. The metal M belongs to ……………. group.
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
Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.
Study the following table in which positions of six elements A, B, C, D, E and F are shown as they are in the modern periodic table:
|
Group→
Period↓ |
1
|
2
|
3-12
|
13
|
14
|
15
|
16
|
17
|
18
|
| 2 | A | B | C | ||||||
| 3 | D | E | F |
On the basis of the above table, answer the following questions:-
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of D and E, which is bigger in size and why?
(v) Write the common name for the family to which the elements C and F belong.
Write the number of vertical columns in the modern periodic table. What are these columns called?
Name the element which is in seventeenth group and second period.
Why do elements in the same group show similar properties but the elements in different groups show different properties?
How does the atomic size vary on going down from top to bottom in a group of the periodic table? Why does it vary this way?
In which part of a group would you separately expect the elements to have the largest atomic size?
In terms of electronic configurations, explain the variation in the size of the atoms of the elements belonging to the same period and same group ?
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
Why sodium element of group 1 and chlorine element of group 17 both have valency 1?
Why are noble gases placed in a separate group?
An element X belong to 4th period and 17th group, state.
no of valence electrons in it
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.
Chemical reactivity of elements ?
Name the element of lower nuclear charge out of Be and Mg.
State the number of elements in periods 1, Periods 2, and Period 3 of the periodic table. Name them.
name the elements in period 1.
How do you calculate the possible valency of an element from the electronic configuration of its atoms?
K, Pb, Ca, Zn (In the increasing order of the reactivity)
State whether the following statement is true or false
Similar electronic configuration is repeated after intervals of 2, 8, 8, 18 and 32.
How could the atomic radius of a noble gas be compared with the other elements in a period?
What is meant by a group in the periodic table?
The following questions refer to the Periodic Table.
What is the common feature of the electronic configurations of the elements in group 7?
In the above table, H does not represent hydrogen.Some elements are given in their own symbol and position in the periodic table while others are shown with a letter. With refrence to the table answer the following questions.
1. Identify the most electronegative element.
2. Identify the most reactive element of Group I.
3. Identify the element from Period 3 with least atomic size.
4. How many valence electrons are present in Q?
5. Which element from group 2 would have the least ionisation energy?
6. Identify the noble gas of the fourth period.
7. In the compound between A and H, what type of bond would be formed and give its molecular formula.
Choose the most appropriate answer from the following list of oxides which fit the description.
A basic oxide.
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 |
Which one of the above elements belongs to the halogen series?
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 most reactive (i) metal (ii) non-metal
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.
Moving down in the second group, number of valence electrons ______.
The electronic configuration of an element is 2, 8, 4. State it:
group and period in the Modern Periodic Table.
The electronic configuration of an element is 2, 8, 4. State it:
name and write its one physical property.
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
Fill in the blanks from the words A to F given below.
A: Decreases
B: Increases
C: Remains same
D: Increases by one
E: Electropositive
F: Electronegative
Down a group in the Modern Periodic Table.
No. of electron shells __________; No. of valence electrons ________; Electronegativity ________ Character of elements changes from _________ to ____________.
