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# Xam Idea Class 9 Science Chapter 4 Solutions: Structure Of The Atom

Xam Idea Class 9 Science Solutions Chapter 4 – Structure of the Atom will help you prepare for your CBSE exams in an easy and organized manner. Our subject matter experts have formed these answers to ensure that you understand the topics of the chapter easily. All our Xam Idea Class 9 Science Solutions for Chapter 4 – Structure of the Atom are created as per the latest CBSE syllabus and NCERT textbooks.

Our Xam Idea Class 9 Science Solutions for Chapter 4 – Structure of the Atom will help you in learning about concepts like atomic mass, atomic number, Thompson’s atomic model, Bohr’s atomic model and the gold leaf experiment. The chapter has very well explained theoretical portions, diagrammatic representations, interactive questions and interesting experiments all of which have been taken care of in our solutions.

Our solutions for Xam Idea Class 9 Science Chapter 4 – Structure of the Atom consist of six exercises. These include short answer type questions, very short answer type questions, long answer type questions, higher-order thinking skills and value-based questions. You will find our solutions fun and interesting to engage with. They cover all the essential portions of the chapter and will also assist you in the process of revising and practising them.  After investing your time in these exercise questions you will be well versed with the concepts like electronic configuration, electron distribution and radii.

## Important Topics for Xam Idea Class 9 Science Solutions Chapter 4 – Structure of the Atom

Canal Rays

In this chapter, you will learn about the concept of canal rays. These rays are deflected by the magnetic fields in a direction that is opposite to that of the cathode rays. You will also study these with respect to charges and learn that they are composed of particles which are positively charged.

Thompson’s Atomic Model

The chapter talks about the atomic model which was presented by scientist J.J. Thompson. He proposed his theory that atoms comprise of a positively charged sphere which has electrons attached to it. The chapter explains the shortcomings of the model as well as the role it played as the foundation for further studies about atoms.

Rutherford’s Atomic Model

In this chapter, you will learn about Rutherford’s Atomic Model. According to Rutherford’s atomic model, the electrons revolved around the nucleus over imaginary paths which were very well defined. He also stated that there is a positively charged centre in the atom which is called its nucleus. His model was a very remarkable milestone but it has many drawbacks like it couldn’t explain the energy loss which would occur in the electrons of an atom.

Bohr’s Atomic Model

A scientist named Neils Bohr also came up with his theory of atomic models. According to his study, there were certain orbits which were known as discrete orbits and the electrons revolved around the nucleus in these orbits only. He also stated that there was no radiation of energy by the electron while they revolved.

Atomic Number

You will get to know that the atomic number of an element is actually the number of protons in an atom of that element. The atomic number can be defined as the total number of protons present in the nucleus of an atom.

Isotopes

In this chapter, you will learn about terms like valency, atomic number and atomic masses. Isotopes is another important term which you will encounter in this chapter. There are some elements which exist with the same atomic number but have a different atomic mass. Such elements are termed as isotopes.

Isobars

These are opposites of isotopes. Elements which have same atomic masses but different atomic numbers are known as isobars.

### Exercise Discussion of Xam Idea Class 9 Science Solutions Chapter 4 – Structure of the Atom

• There are a total of 20 questions in this exercise.
• The first question asks which sum atomic particle is absent in case of an ordinary hydrogen atom.
• The second question requires you to identify and name the particle that has been described in the question along with its location.
• Question three asks if it is possible for an atom of an element to have one electron, one proton and no neutron.
• The fourth question puts forth a situation where an atom has both negative and positive charge but it is neutral and you need to give the reason for this occurrence.
• The fifth question requires you to give the electronic configuration of an element with the atomic mass 12.
• The sixth question also requires you to explain your understanding of the ground state of an atom.
• The seventh question asks you to give the number of maximum electrons which can be accommodated in the N shell.
• The eighth question requires you to give the correct representation of element x with 15 electrons and 16 neutrons.
• The ninth question works on the fundamentals of electrons.
• Question ten presents a bunch of elements and you are required to detect which of them are isotopes. Question eleven also revolves around the same concept.
• Question twelve and thirteen test your understanding of the shells, electrons and ions in an atom.
• The fourteenth question requires you to give two applications of radioactive isotopes.
• Question fifteen inquires which isotope of hydrogen is present in heavy water.
• Question sixteen requires you to give the formula of chloride based on the formula of metal sulphide.
• In question number seventeen you need to give the formula of the compound with respect to the information that has been given in the question.  Question eighteen also works on the same concept.
• The last question requires you to identify the pair of elements on the basis of information shared in the question statement.

• This exercise has a total of 15 questions.
• The exercise begins with a question requires you to explain how do you know the size of the nucleus is small as compared to that of the atom.
• You need to give two characteristics of the canal rays in question two
• Question three and four revolve around the idea of the electronic configuration
• in question five you need to find the number of electrons in the ions of aluminium and chlorine
• Question six requires you to give the electronic distribution of an atom of chlorine and fine the number of electrons in the L shell.
• Question seven requires you to define valence electrons
• Question eight is a reasoning based question where you need to tell why helium and neon have null valency.
• Question nine requires you to reflect why helium has two electrons in this valence shell but its valency is mot two
• Question ten is a diagram-based question where you need to find the valency of the atoms depicted in the figure
• Question eleven requires you to identify the sodium ion from the figures given in the question, find its valency and give reasons for your answer
• Question twelve requires you to calculate the number of neutrons that are present in the nucleus of the element given in the question
• Question thirteen requires you to describe by isotopes have similar chemical properties
• Question fourteen requires you to write the formula of the element X with phosphide and carbonate
• The last question gives information about an element and requires you to find its valency and determine if it is a non-metal or a metal.

• This exercise has 12 questions
• The exercise begins with a question which requires you to distinguish between the atomic models of Rutherford and Thompson.
• Question two to nine are all numerical based questions based on formula formation, valency, number of particles and mass number.
• Question ten presents a set of compounds and you are required to write the molecular formula of those compounds.
• The last two questions also require you to give molecular formulas of the elements with respect to their ions.

• There are a total of seven questions in this exercise
• The first question is theory-based and requires you to give a method in order to determine the valency and an atomic number of an element.
• The second question requires you to explain the gold foil experiment and give conclusions and shortcomings of it
• The third question requires you to explain how Rutherford’s atomic model was different from Thompson.
• Question four requires you to give the postulates of Bohr’s atomic model of an atom.
• Question five is a numerical problem which requires you to estimate the magnitude of the nucleus of an atom with the help of all the details that have been provided in the question.
• Question seven requires you to give the diagrammatic representation of the electronic distribution in the sodium atom and the sodium ion.
• The last question presents the diagram of the atomic structure of an element and requires you to find its atomic number, its atomic mass, the number of valence electrons, its valency and determine whether or not it is a metal.

### Why Use Xam Idea Class 9 Science Solutions Chapter 4 – Structure of the Atom

• To simplify your course of understanding our subject matter experts have created Xam Idea Solutions for Chapter 4 – Structure of the Atom in a stepwise manner.
• All the Xam Idea Class 9 Science Chapter-wise solutions are in accordance with the latest CBSE curriculum and exam pattern.
• We have ensured that each and every question from the chapter has been entertained and resolved with care in order to solve all your confusions at one place.
• Our Xam Idea Class 9 Science Solutions for Chapter 4 – Structure of the Atom are free to access by all.
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