Give the number of protons, electrons, and neutrons in the following : Na 11 23 P 15 31 Cl 17 35 Give the electronic distribution of these atoms and also predict the valency in each case.

i) Sodium Na 11 23 , Number of protons = Number of electrons = 11 . Number of neutrons = 23 - 11 = 12 . Electronic configuration of sodium is 2 , 8 , 1 . Since it has to complete its octet, so it will donate 1 electron from outermost orbit. So, valency of sodium is 1 . ii) Phosphorous P 15 31 , Number of protons = Number of electrons = 15 . Number of neutrons = 31 - 15 = 16 . Electronic configuration is 2 , 8 , 5 . Since it has to complete its octet, so it will accept 3 electrons from outermost orbit. So, valency is 3 . iii) Chlorine Cl 17 35 , Number of protons = Number of electrons = 17 . Number of neutrons = 35 - 17 = 18 . Electronic configuration is 2 , 8 , 7 . Since it has to complete its octet, so it will accept 1 electron from outermost orbit. So, valency of is 1 .

Complete the following table: Mass number Atomic number Number of protons Number of neutrons Name of the element 31 15 - - - - - 12 12 - - 17 - 18 -

Given, Mass number = 31 and Atomic number = 15 . We know that, Number of protons = Atomic number = 15 . Hence, number of protons is 15 . Number of neutrons = Mass number - Number of protons. Hence, number of neutrons = 31 - 15 = 16 . Thus, the name of the element is phosphorous. Given, Number of protons = 12 and Number f neutrons = 12 . We know that, Atomic number = Number of protons = 12 . Hence, atomic number is 12 . Mass number = Number of protons + Number of neutrons. Mass number = 12 + 12 = 24 . Thus, the name of the element is magnesium. Given, Atomic number = 17 and number of neutrons = 18 . We know that, Number of protons = Atomic number = 17 . Hence, number of protons is 17 . Mass number = Number of protons + Number of neutrons. Mass number = 17 + 18 = 35 . Thus, the element is chlorine. Mass number Atomic number Number of protons Number of neutron Name of the element 31 15 15 31 - 15 = 16 Phosphorous P 24 12 12 12 Magnesium Mg 35 17 17 18 Chlorine Cl

E M B I B E

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE

S K Malhotra Solutions for Chapter: Structure of Atom, Exercise 1: TEST YOUR KNOWLEDGE

Author:S K Malhotra

S K Malhotra Chemistry Solutions for Exercise - S K Malhotra Solutions for Chapter: Structure of Atom, Exercise 1: TEST YOUR KNOWLEDGE

Attempt the free practice questions on Chapter 4: Structure of Atom, Exercise 1: TEST YOUR KNOWLEDGE with hints and solutions to strengthen your understanding. Super Simplified Science Chemistry CLASS IX solutions are prepared by Experienced Embibe Experts.

Questions from S K Malhotra Solutions for Chapter: Structure of Atom, Exercise 1: TEST YOUR KNOWLEDGE with Hints & Solutions

MEDIUM

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 35

Give the number of protons, electrons, and neutrons in the following :

${}_{11}^{23}{Na}$ ${}_{15}^{31}P$ $1$

Give the electronic distribution of these atoms and also predict the valency in each case.

HARD

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 36

How were cathode rays discovered by Thomson? Describe with the help of an experiment.

MEDIUM

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 37

Define the terms atomic number and mass number. How are they related to each other? In which case the atom of the element has same number of protons and electrons?

HARD

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 38

Discuss the main features of Rutherford scattering experiment. What are the limitations of this model of the atom?

MEDIUM

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 39

Complete the following table:

Mass number	Atomic number	Number of protons	Number of neutrons	Name of the element
$31$	$15$	$-$	$-$	$-$
$-$	$-$	$12$	$12$	$-$
$-$	$17$	$-$	$18$	$-$

EASY

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 40

What are isotopes? What is common in the isotopes of an element. Give the representations of the three isotopes of carbon which are $C - 12, C - 13, C - 14$ .

MEDIUM

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 41

How will you account for the following?

(i) An atom is electrically neutral

(ii) Isotopes of an element are chemically similar

(iii) Nucleus of an atom is massive and positively charged in nature.

MEDIUM

9th CBSE

IMPORTANT

Super Simplified Science Chemistry CLASS IX>Chapter 4 - Structure of Atom>TEST YOUR KNOWLEDGE>Q 42

An ion $M^{3 +}$ contains $10$ electrons and $14$ neutrons. What are the atomic number and mass number of the element $M$ ? Name the element. Give its electronic distribution and predict its valency.

Learn and Prepare for any exam you want !

|

|

|

|

|

|

|

|