Symbols Br 35 79 and Br 79 can be written, whereas symbol Br 79 35 and Br 35 are not acceptable. Answer briefly.

The general convention of representing an element along with its atomic mass A and atomic number Z is X Z A . Hence, Br 35 79 is acceptable but Br 79 35 is not acceptable. Br 79 can be written but Br 35 cannot be written because the atomic number of an element is constant, but the atomic mass of an element depends upon the relative abundance of its isotopes. Hence, it is necessary to mention the atomic mass of an element.

E M B I B E

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.37

HARD

11th CBSE

IMPORTANT

Earn 100

The diameter of zinc atom is $2.6 \overset{\circ}{A}$ . Calculate (a) radius of zinc atom in $pm$ and (b) number of atoms present in a length of $1 .6 cm$ if the zinc atoms are arranged side by side lengthwise.

Important Questions on Structure of Atom

MEDIUM

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.38

A certain particle carries

2.5 \times 10^{- 16} C

of static electric charge. Calculate the number of electrons present in it.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.39

In Millikan’s experiment, static electric charge on the oil drops has been obtained by shining X-rays. If the static electric charge on the oil drop is

- 1 .282 \times 10^{- 18} C

, calculate the number of electrons present on it.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.4

In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the α-particles. If the thin foil of light atoms like Aluminium etc. is used, what difference would be observed from the above results ?

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.41

Symbols

{}_{35}^{79}{Br}

and

{}^{79}{Br}

can be written, whereas symbol

{}_{79}^{35}{Br}

and

{}^{35}{Br}

are not acceptable. Answer briefly.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.42

An element with mass number

81

contains

31.7 %

more neutrons as compared to protons. Assign the atomic symbol.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.43

An ion with mass number

37

possesses one unit of negative charge. If the ion contains

11.1 %

more neutrons than the electrons, find the symbol of the ion.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.44

An ion with mass number

56

contains

3

units of positive charge and

30.4

% more neutrons than electrons. Assign the symbol to this ion.

HARD

11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.45

Arrange the following type of radiations in increasing order of frequency: (a) radiation from microwave oven (b) amber light from traffic signal (c) radiation from FM radio (d) cosmic rays from outer space and (e) X-rays.