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Questions and Answers
What quantum number denotes the orbital number or shell number of an electron?
What quantum number denotes the orbital number or shell number of an electron?
Which phenomenon is defined as the deflection of electrons in the presence of an electric field?
Which phenomenon is defined as the deflection of electrons in the presence of an electric field?
Who concluded that nature is symmetrical, so light or any other matter wave should be symmetrical?
Who concluded that nature is symmetrical, so light or any other matter wave should be symmetrical?
Which rule states that electrons should be filled according to the ascending order of energy of orbitals?
Which rule states that electrons should be filled according to the ascending order of energy of orbitals?
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What does the Spin Quantum number represent?
What does the Spin Quantum number represent?
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What principle states that no two electrons can have all four quantum numbers the same?
What principle states that no two electrons can have all four quantum numbers the same?
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According to Hund's Rule of Maximum Multiplicity, how should degenerate orbitals be filled?
According to Hund's Rule of Maximum Multiplicity, how should degenerate orbitals be filled?
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What does the electron configuration of an element describe?
What does the electron configuration of an element describe?
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Which quantum number denotes the shape of an atomic orbital?
Which quantum number denotes the shape of an atomic orbital?
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Why are electron configurations useful in predicting the properties of elements?
Why are electron configurations useful in predicting the properties of elements?
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Study Notes
Atomic Structure
- Atoms of different elements have unique characteristics due to their distinct atomic structures, which are determined by the number of protons and electrons.
Dalton's Atomic Theory
- Proposed by John Dalton in the 18th century
- Postulates:
- Matter is composed of atoms, which are indivisible and indestructible
- All atoms of an element are identical, but different elements have different atoms
- Chemical reactions involve the rearrangement of atoms
- Atoms cannot be created or destroyed, only transformed
- Successfully explained laws of chemical reactions, including the Law of Conservation of Mass and the Law of Definite Proportions
- Limitations: unable to explain the existence of isotopes and the structure of atoms
Thomson Atomic Model
- Proposed by J.J. Thomson in the early 1900s
- Describes the atomic structure based on the cathode ray experiment
- Discovery of electrons, which are negatively charged subatomic particles
Rutherford Atomic Theory
- Proposed by Ernest Rutherford, a student of Thomson
- Modified the atomic structure with the discovery of the nucleus
- Atomic model based on the alpha ray scattering experiment
- Nucleus is at the center of the atom, with electrons orbiting around it in circular paths
- Limitations: unable to explain the stability of atoms and the line spectrum observed
Atomic Structure - Rutherford's Model
- Nucleus is at the center of the atom, where most of the charge and mass is concentrated
- Electrons revolve around the nucleus in circular orbits
- Protons and neutrons make up the nucleus
- Electrons are negatively charged and much lighter than protons and neutrons
Subatomic Particles
- Protons:
- Positively charged
- Charge: 1e (approximately 1.602 × 10^-19)
- Mass: approximately 1.672 × 10^-24
- Neutrons:
- Electrically neutral
- Mass: approximately 1.674 × 10^-24
- Electrons:
- Negatively charged
- Charge: -1e (approximately -1.602 × 10^-19)
- Mass: approximately 9.1 × 10^-31
Isotopes
- Variants of an element with the same atomic number but different mass numbers
- Differ in the number of neutrons in their nuclei
- Examples: protium, deuterium, and tritium (isotopes of hydrogen)
Bohr's Atomic Theory
- Proposed by Niels Bohr in 1915
- Postulates:
- Electrons occupy discrete orbits (stationery orbits) around the nucleus
- Energy levels of these shells can be represented by quantum numbers
- Electrons can jump to higher energy levels by absorbing energy and move to lower energy levels by emitting energy
- Limitations: unable to explain the spectra of multi-electron species and the Stark and Zeeman effects
Quantum Mechanics
- Heisenberg's uncertainty principle: no two conjugate physical quantities can be measured simultaneously with 100% accuracy
- Pauli's exclusion principle: no two electrons can have the same set of four quantum numbers
- Hund's rule of maximum multiplicity: degenerate orbitals must be singly filled first, then paired
Electronic Configuration
- The distribution of electrons in atomic orbitals
- Determines the valency of an element and can be used to predict the properties of a group of elements
- Examples: electron configuration of sodium is 1s2 2s2 2p6 3s1
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Description
Test your knowledge on Rutherford's Atomic Theory, which introduced the concept of the nucleus in an atom based on the Alpha ray scattering experiment. Learn about the spherical atomic structure proposed by Rutherford and the key features of his atomic model.
