Number of Elements in a Period

Q.

The modern periodic table was given by:

1. Newlands

2. Dobereiner

3. Bohr

4. Mendeleev

Q. Name the elements which have the smallest and the largest atom?

Q.

Explain the merits of modern periodic table?

Q. How many elements are there in period 2?

Q.

The element in the third period having three valence electrons is _______.

Q. Find the block to which Magnesium, the atomic number is 12, belong.

1. s
2. p
3. d
4. f

Q.

Which is the longest group in periodic table?

Q. is it necessary to learn whole periodic table if not then till which element should i learn??

Q.

What is the common feature of the electronic configuration of the element in group 7.

Q.

(a) How were the positions of isotopes of an element decided in the modern periodic table ?

(b) How were the positions of cobalt and nickel resolved in the modern periodic table ?

(c) Where should hydrogen be placed in the modern periodic table ? Give reason for your answer.

Q.

Which of the following is the outermost shell for elements of period 2?

1. K shell

2. L shell

3. M shell

4. N shell

Q.

The number of elements in each of the long periods are__.

1. 18

2. 8

3. 2

4. 32

Q.

State the variable valency of the metal silver.

Q. To which group and period does the element with electronic configuration 2, 8, 4 belong in the modern periodic table?

[1 mark]

1. $1^{st}period,1^{st}group$
2. $3^{rd}period,{14}^{th}group$
3. $3^{rd}period,3^{rd}group$
4. $2^{nd}period,{15}^{th}group$

Q.

Which of the following is the valence shell for the elements of the second period of the modern periodic table?

(a) M shell (b) K shell (c) L shell (d) N shell

Q.

Write a short note on electronic view of non-metals. [3 MARKS]

Q. in which group and period hydrogen should be placed 1. in mendeleevs periodic table 2. in modern periodic table

Q.

State the modern periodic law. Name the scientist who stated this law.

Q.

In the following set of elements, one element does not belong to the set. Select this element and state why it does not belong :

Oxygen, Nitrogen, Carbon, Chlorine, Fluorine

Q. Which of the following are the important merits of modern periodic table?

1. It explains why element in the same group have the same chemical properties.
2. Hydrogen has been placed accurately.
3. Isotopes have been placed at same position.
4. It is based on classifying elements according to their atomic number.

Q. An element X has electronic configuration 2, 8, 8, 2. Which period of the modern periodic table does this element belong to?

1. 3
2. 4
3. 2
4. 5

Q.

An element has two electron in its N shell .
1) what is it atomic number ?
2) state the position in periodic table ?
3) is it a metal or non metal ?
4) state the name assigned to this group ?

Q.

The atomic number of an element is 20. In the modern periodic table, this element is placed in :

(a) 2nd period (b) 4th period (c) 3rd period (d) 1st period

Q.

Na⁺ have completely filled K and L shells explain.

Q.

Why are the Lanthanides and the Actinides given a separate position in the modern periodic table?

Q. Explain periodic law given by mendeleev in detail

Q.

According to modern periodic table, the chemical properties of elements are periodic function of their____________________

Q.

Name the following:

How many elements are there in the first period in the modern periodic table?

Q. 1. Mendeleevs periodic table did not have noble gases in it. Then how come Ar, Ca be placed as anomalous pair( pair in which heavier mass elent has been placed first with the lighter mass element next)?

Q.

Give two examples of cations having completely filled K and L shells.