Quantum Mechanical Model of Atom

Quantum Mechanical Model of Atom

by DESIREE JAWA, ETSS01

​Objectives:

• Understand the different atomic models that led to the formulation of Quantum Mechanical Model of atom.

• ​Explain how the Quantum Mechanical Model of the atom describes the energies and positions of the electrons.

Fill in the Blank

Matter consists of exceedingly tiny particles called _____?

Multiple Choice

It is the simplest or pure substance which contains the same type of atom.

• Element

• Compound

• Molecule

• Solution

Multiple Choice

What do you call the negatively charged subatomic particle?

• Proton

• Electron

• Neutron

• Nucleus

Multiple Choice

The uncharged subatomic particles with a mass approximately similar to protons are called ________.

• Neutrons

• Neutral

• Nucleus

• Isotopes

Multiple Choice

What is the nucleus of an atom composed of?

• Protons and Electrons 

• Neutrons and Electrons 

• Protons and Neutrons 

• Photons 

THE DEVELOPMENT OF

QUANTUM MECHANICAL MODEL​

• ​Bohr Model of Atom

• ​De Broglie's Wave-Particle Duality

• ​Schrödinger's Electron Cloud Model

• ​Heisenberg's Uncertainty Principle

​The Bohr Model of Atom

​Niels Bohr

​​- Danish physicist

​- Resolved Rutherford's Nuclear Model of Atom

​- Bohr assumed that the energies of the electron orbital were quantized.

​© University of California Museum of Paleontology's Understanding Science (http://www.understandingscience.org)

​The Bohr Model of Atom

Quantization of Energy

- Max Planck introduced the term "quantum" in the field of physics in the notion of "minimum amount of a quantity which can exist"

​- Electrons could only occupy particular orbits or

energy levels determined by the quantum of action.

​

​The Bohr Model of Atom

Quantization of Energy

​​Energy level or the principal quantum number is denoted by n with values 1, 2, 3, 4, ... ​​

or by letters K, L, M, N

​

​Electron capacity = 2n²

​​n = 1 ➡ 2 electrons

n = 2 ➡ 8 electrons

​ n = 3 ➡ 18 electrons

​ n = 4 ➡ 32 electrons

​The Bohr Model of Atom

​© LumenLearning.com

​Hydrogen Atomic Emission Spectrum

​The Bohr Model of Atom

Limitations to Bohr's Theory

​- It cannot be applied to multielectron atoms.

​- Orbits are not circular paths. Electrons do not follow a well-defined path, rather there is a cloud of probability (quantum mechanical model).

louis de broglie's theory

​- French physicist

- In 1924, he proposed the wave-particle duality of electrons

​Erwin Schrödinger's electron cloud model

​- Austrian theoretical physicist

​- In 1926, Erwin Schrödinger extended de Broglie's work by deriving what is today known as the Schrödinger equation. He used mathematical equations to describe the probability of finding an electron in a certain region in space, or orbitals.

concept mapping

Interactive Whiteboard Activity:

​Fill out the concept map by clicking this link:

https://app.nearpod.com/?pin=BEMXC

QUANTUM NUMBERS

The Principal Quantum Number ( n )

​The principal quantum number is an integer that determines the overall size and energy of an orbital. Its possible values are n = 1, 2, 3, ... and so on.

​©Chemistry LibreTexts. Atomic Orbitals and Quantum Numbers. (https://chem.libretexts.org/@api/deki/files/71006/CNX_Chem_06_03_Qnumbers.jpg?revision=1)

QUANTUM NUMBERS

The Angular Momentum Quantum Number ( l )

​The angular momentum quantum number is an integer that determines the shape of the orbital. The possible values of l are 0, 1, 2, ... (n - 1).

​© Angular Momentum Quantum Number. (https://study.com/cimages/multimages/16/angularmomentumshapes2.png)

QUANTUM NUMBERS

The Magnetic Quantum Number ( m_l )

​The magnetic quantum number is an integer that specifies the orientation of the orbital. The possible values of m_l are the integer values (including zero) ranging from -l to +l . For example, if l = 0, then the only possible value of ml is 0; if l = 1, the possible values of ml are -1, 0, and +1.

​©Protons Talk. Four Quantum Numbers. (https://protonstalk.com/wp-content/uploads/2021/08/Electron-Orbitals-as-per-Quantum-Numbers1-1024x601.jpg)

QUANTUM NUMBERS

The Spin Quantum Number ( m_s )

​The spin quantum number specifies the orientation of the spin of the electron. Electron spin is a fundamental property of an electron (like its negative charge). The orientation of the electron’s spin is quantized, with only two possibilities that we can call spin up ( m_s = +1/2) and spin down ( m_s = -1/2).

​©The Physical Significance of the 4 Quantum Numbers. (https://web.fscj.edu/Milczanowski/psc/lect/Ch8/SLIDE96.jpg)

QUANTUM NUMBERS

Summary

QUANTUM NUMBERS

PRACTICE

​Access this link: https://app.nearpod.com/?pin=TPVJX and fill the table with the correct quantum numbers.