Concise Chemistry Class 9 ICSE Solutions for Chapter 4 - Atomic Structure and Chemical Bonding

Q: 5. What is an α (alpha) particle?

An α-particle is a doubly charged helium ion (He2+) which consists of two protons and two neutrons. It is formed based on removing two electrons from the helium atom. They are emitted from the nucleus which is known as radionuclides which happens during the time of radioactive decay and this is known as alpha decay. Alpha particles were the first nuclear radiation to be discovered. Beta particles, as well as gamma particles, were discovered later on.

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Concise Chemistry Class 9 ICSE Solutions for Chapter 4 - Atomic Structure and Chemical Bonding

ICSE Class 9 Chemistry Chapter 4 Selina Concise Solutions - Free PDF Download

Updated ICSE Class 9 Chemistry Chapter 4 - Atomic Structure And Chemical Bonding Selina Solutions are provided by Vedantu in a step-by-step method. Selina is the most famous publisher of ICSE textbooks. Studying these solutions by Selina Concise Chemistry Class 9 Solutions which are explained and solved by our subject matter experts will help you in preparing for ICSE exams. Concise Chemistry Class 9 ICSE Solutions can be easily downloaded in the given PDF format. These solutions for Class 9 ICSE will help you to score good marks in ICSE Exams 2024-25.

The updated solutions for Selina textbooks are created in accordance with the latest syllabus. These are provided by Vedantu in a chapter-wise manner to help the students get a thorough knowledge of all the fundamentals.

Atomic Structure

The atomic structure is described as the form of an atom which consists of the nucleus in the centre and in that protons which are positively charged and neutral neutrons are present and the negatively charged electrons rotate around the centre of the nucleus. They are the building blocks of matter and it is the smallest constituent unit of matter which has the properties of the chemical element.

Atoms are too rare to be seen; thus, studies to figure out their structure and behaviour have to be performed with many of them. Based on the result of their experiments, we may try to create a hypothetical model of an atom that behaves like an actual atom.

There was this Greek philosopher Democritus who discovered the theory of the atom around 450 B.C. In essence, however, the approach has been overlooked.

It was John Dalton who reintroduced the atom in 1800. He has also provided proof after a deep study of the atoms and has established and developed atomic theory. His principle is fundamentally correct. Although, he was incorrect to think that atoms are the smallest particles of matter.

It was in the year 1897 J.J. Thomson discovered electrons. He suggested and discovered the concept of the atom’s plum pudding. Based on this model, negative electrons are dispersed throughout the “sea” of a positive charge.

Isotopes:

Isotopes are described and classified as varieties of chemical elements with the same number of protons and electrons but a different number of neutrons in there. In other words, isotopes are types of elements that have an unequal number of neutrons but equal protons.

FAQs on Concise Chemistry Class 9 ICSE Solutions for Chapter 4 - Atomic Structure and Chemical Bonding

1. What are subatomic particles?

Subatomic particles are also known as elementary particles and refer to any self-contained units or energy that are fundamentally the composition of all matter. Subatomic particles are the particles that help in forming an atom. Generally speaking, this word refers to protons, electrons(which are almost massless particles), and neutrons. They are a very dense nucleus of the atom. Both of them are made up of quarks which are elementary particles. Students should study and understand the topics which will help them to answer well in the exam.

2. How do isotope atomic structures vary?

The nucleus differs because of the number of neutrons present in it. The actual structure does not differ that much and therefore the density of it is a little different. The reason behind this is the number of neutrons present in the nucleus at the centre of the atom. In the case of isotopes, they have the same number of protons in the same element but they have an unequal number of neutrons. Students should study thoroughly and understand the concepts of protons and neutrons.

3. What are the drawbacks of the Bohr atomic model?

Thomson and Rutherford, their atomic model failed to answer any question regarding the energy of the atom and also related to its stability. Niels Bohr (1913 ) proposed an atomic structure model on the basis that the atom is a small, positively charged nucleus that is surrounded by electrons that rotate in circular orbits around the positively charged nucleus and with attraction provided by electrostatic forces, popularly known as Bohr’s atomic model. According to this atomic model, the structure of the atom provides poor spectral estimates of larger atoms. It also failed to explain and clarify the influence of Zeeman. The hydrogen continuum is the only part that is explained effectively.

4. How did Bohr find the electrons?

Bohr had discovered this concept in the year 1913. He used to believe that the size of the electrons is depending on the size of the orbit and is lower with the smaller orbits. Electrons move with fixed size and energy and it travels around the nucleus in various orbits and the properties of the element depending on the number of electrons present in the outer orbit. It is very important to study the properties of elements and revise every day so that there is no confusion at the end moment.

5. What is an α (alpha) particle?

An α-particle is a doubly charged helium ion (He₂⁺) which consists of two protons and two neutrons. It is formed based on removing two electrons from the helium atom. They are emitted from the nucleus which is known as radionuclides which happens during the time of radioactive decay and this is known as alpha decay. Alpha particles were the first nuclear radiation to be discovered. Beta particles, as well as gamma particles, were discovered later on.