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The Fundamental Unit Of Life

Question
CBSEENSC9005234
Wired Faculty App

Give the nuclear composition and electronic configuration of 18 elements with atomic number 1 to 20.

Solution

Name of element

Symbol

Atomic number

Number of protons

Number of Neutrons

Number of Electrons

Distribution of Electrons

Valency

 

K

L

M   N

 

Hydrogen

H

1

1

0

1

1

-

-

-

1

Helium

He

2

2

2

2

2

-

-

-

0

Lithium

Li

3

3

4

3

2

1

-

-

1

Beryllium

Be

4

4

5

4

2

2

-

-

2

Boron

B

5

5

6

5

2

3

-

-

3

Carbon

C

6

6

6

6

2

4

-

-

4

Nitrogen

N

7

7

7

7

2

5

-

-

3

Oxygen

O

8

8

8

8

2

6

-

-

2

Fluorine

F

9

9

10

9

2

7

-

-

1

Neon

Ne

10

10

10

10

2

8

-

-

0

Sodium

Na

11

11

12

10

2

8

1

-

1

Magnesium

Mg

12

12

12

12

2

8

2

-

2

Aluminium

Al

13

13

14

13

2

8

3

-

3

Silicon

Si

14

14

14

14

2

8

4

-

4

Phosphorus

P

15

15

16

15

2

8

5

-

3

Sulphur

S

16

16

16

16

2

8

6

-

2

Chlorine

Cl

17

17

18

17

2

8

7

-

1

Argon

Ar

18

18

22

18

2

8

8

-

0

Some More Questions From The Fundamental Unit of Life Chapter

Compare all the proposed models of an atom given in this chapter.

Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.

Define valency by taking examples of silicon and oxygen.

Explain with examples, (i) Atomic number, (ii) Mass number, (iii) Isotopes, and (iv) Isobars. Give any two uses of isotopes also.

Na+ has completely filled K and L-shells. Explain.

If Z = 3, what would be the valency of the element? Also, name the element.

Composition of the nuclei of two atomic species X and Y are given as under


                              X        Y
Protons  =                6        6
Neutrons=                6        6

Give the mass numbers of X and Y. What is the relation between the two species?

For the following statements, write T for True and F for False.

(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.

(c) The mass of an electron is about 1/2000 times that of proton.

(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.

Rutherford’s α-particle scattering experiment was responsible for the discovery of

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