Quantum Mechanical Model Of Atom
Chapter Name : Structure Of Atom |
Sub Topic Code : 102_11_02_06_05 |
Topic Name : Quantum Mechanical Model Of Atom |
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Sub Topic Name : Filling Of Orbitals In An Atom |
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Introduction
• Electrons are filled in orbitals present in the shells of an atom. • The filling of electrons is governed by 3 rules: Aufbau principle, Pauli’s exclusion principle and Hund’s rule of maximum multiplicity. • The Aufbau principle states that filling of electrons starts from the orbital having lowest energy. • Pauli’s exclusion principle states that no electron can have the same set of quantum numbers. • Hund’s rule of max. Multiplicity states that electrons fill each orbital in the sub-shell before they start pairing up.
Pre-Requisites:
• Definition of atom and its constituents • Quantum numbers and orbitals • Energy of orbitals
Real Life Question:
Can an atom have an empty 1st shell and a filled 2nd shell?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
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| Atomic Orbital | The wave function of an electron in an atom or molecule, indicating the electron's probable location. |
| Quantum numbers | They are a set of values that describe the state of an electron including its distance from the nucleus, the orientation and type of orbital where it is likely to be found, and its spin. |
| Principal quantum number | The principal quantum number (n) gives the number of the electron shell in an atom. |
| Azimuthal quantum number | Azimuthal quantum number (l) tells us about the shape of an orbital. |
| Magnetic quantum number | Magnetic quantum number (ml) gives the orientation of an orbital (integers from –l to l, for p = -1, 0, 1). |
| Spin quantum number | Spin quantum number (ms) gives the spin of an electron (either -½ or ½). |
Learning aids / Gadgets
| Gadgets | How it can be used |
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Practical examples around us
| Examples | Explainations |
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What you learn in Theory:
Rules governing the filling of electrons in an atom.