Questions and Answers
What is the fundamental building block of matter?
Why do objects become electrically charged when rubbed together?
Who identified the electron?
What was the term given by E. Goldstein to the new radiations in a gas discharge?
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What was the major challenge before scientists at the end of the 19th century?
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What is the reason for the existence of different kinds of matter?
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What was Dalton's proposal about atoms?
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What is the name of the chapter that deals with the structure of the atom?
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What is the significance of the discovery of canal rays?
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What is the symbol used to denote the mass number of an atom?
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What is the valency of fluorine according to the content?
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What is the valency of oxygen calculated from the content?
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What is the combining capacity of an atom known as?
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What is the number of protons present in the nucleus of an atom known as?
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What is the notation for an atom that includes the atomic number, mass number, and symbol of the element?
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What is the atomic number of an atom with 8 electrons and 8 protons?
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What is the purpose of knowing the valency of an element?
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What is the term used to describe the different atoms of the same element with different mass numbers?
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What is the reason for calculating the average mass of an element?
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Who is credited with the discovery of electrons?
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What was the major limitation of Rutherford's model of the atom?
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What is the significance of the atomic shells being complete in Bohr's model?
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What is the term used to describe atoms that have the same atomic number but different mass numbers?
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Who discovered the presence of neutrons in the nucleus of an atom?
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What was the significance of Rutherford's alpha-particle scattering experiment?
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What is the term used to describe atoms that have the same mass number but different atomic numbers?
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What is the distribution of electrons in Neils Bohr's model of the atom?
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What is the charge of neutrons?
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What determines the valency of an atom?
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What is the atomic number of an element?
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What is the difference between isotopes and isobars?
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What is the mass of an electron compared to the mass of a hydrogen atom?
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What are the shells of an atom designated as?
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What determines the element of an atom?
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What is the mass number of an atom?
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What is the term for the combining capacity of an atom?
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What was discovered through Rutherford's alpha-particle scattering experiment?
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What is the characteristic that defines isotopes of an element?
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How many valence electrons are present in a Cl– ion?
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What is the correct electronic configuration of sodium?
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What can be inferred about the atomic species with 10 neutrons and 9 protons?
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What is the number of protons in the atomic species with 16 neutrons and named sulphur?
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What can be inferred about the atomic species with 24 protons and 12 electrons?
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What is the number of neutrons in the atomic species with 2 protons and 1 electron?
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What can be inferred about the atomic species with 1 proton and no neutrons?
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Study Notes
Structure of the Atom
- Atoms are the fundamental building blocks of matter, and their existence is due to different atoms constituting them.
Atomic Number and Mass Number
- Atomic number is the number of protons present in the nucleus of an atom.
- Mass number is the sum of the total number of protons and neutrons present in the nucleus of an atom, denoted by 'A'.
- Atomic number, mass number, and symbol of the element are to be written as:
ZXA
.
Valency
- Valency is the combining capacity of an atom, which can be calculated by identifying the number of electrons in the outermost shell.
- Elements have a definite combining capacity, and valency can be calculated for different elements.
Sub-atomic Particles
- Electrons are negatively charged, protons are positively charged, and neutrons have no charge.
- Electrons are embedded in a positive sphere (proposed by J.J. Thomson).
- Protons and neutrons are present in the nucleus of an atom.
- Neils Bohr proposed that electrons are distributed in different shells with discrete energy around the nucleus.
Rutherford's Model
- Rutherford's alpha-particle scattering experiment led to the discovery of the atomic nucleus.
- Rutherford proposed that a very tiny nucleus is present inside the atom, and electrons revolve around this nucleus.
Limitations of Models
- Limitations of J.J. Thomson's model: did not explain the stability of the atom.
- Limitations of Rutherford's model: did not explain the stability of the atom.
- Neils Bohr's model was more successful in explaining the stability of the atom.
Isotopes and Isobars
- Isotopes are atoms of the same element, which have different mass numbers.
- Isobars are atoms having the same mass number but different atomic numbers.
- Elements are defined by the number of protons they possess.
Electronic Configuration
- Shells of an atom are designated as K, L, M, N, etc.
- Valency is related to the electronic configuration of an atom.
- The electronic configuration of an atom can be written by identifying the number of electrons in different shells.
Exercises and Questions
- Compare the properties of electrons, protons, and neutrons.
- Describe Bohr's model of the atom.
- Explain the rules for writing the distribution of electrons in various shells for the first eighteen elements.
- Define valency by taking examples of silicon and oxygen.
- Explain isotopes, mass number, atomic number, and isobars with examples.
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Description
Test your knowledge of atomic structure, including atomic number, mass number, and valency. Learn about the building blocks of matter and how atoms are constituted.