Atomic Structure — Advanced
Chemistry Notes
1. Introduction to Atomic Structure:
➢ According to Dalton atom is the smallest indivisible particle of matter.
● Atom : The smallest unit of matter that retains the properties of
element.
● Atoms consist of three fundamental subatomic particles:
● Protons (+ charge, ~1 amu)
● Neutrons (neutral, ~1 amu)
● Electrons (-charge,~1/1836 amu)
● Atomic Number (Z): Number of protons in the nucleus; defines the element.
● Mass Number (A): Total number of protons + neutrons.
● Isotopes: Atoms of the same element with different numbers of neutrons.
2. Historical Models of Atomic Structure :
Model Description Key limitations
Contribution
•Dalton's atom as a Atomic theory No internal
Model solid, based on structure
Indivisible elements
Sphere
•Thomson’s “Plum Discovery of No nucleus
, Model Pudding” electron
Electrons
embedded in
Positive sphere
•Rutherford Nucleus with Discovery of Could not
Model Protons, nucleus via explain
electrons gold foil electron
Orbiting experiment stability
nucleus
•Bohr Electrons orbit Explanation of only works
Model nucleus in hydrogen perfect for
fixed shells emission H atom
(quantized) spectra
•Quantum Electron Modern atomic Complex
Mechanical Probability theory mathematics
Model Clouds, involved
wavefunctions
(Schrödinger
equation)
3. Key Concepts in Quantum Atomic Structure
3.1 Wave-Particle Duality
•Electrons exhibit both particle and wave-like behavior.
•De Broglie wavelength:
λ= h/mv
Where h = plank's constant ,
m = mass ,
v = Velocity.
3.2 Heisenberg Uncertainty Principle:
• It is impossible to simultaneously know the exact position and momentum of an electron:
° { ∆x.∆p = ≥ h / 4π }
Chemistry Notes
1. Introduction to Atomic Structure:
➢ According to Dalton atom is the smallest indivisible particle of matter.
● Atom : The smallest unit of matter that retains the properties of
element.
● Atoms consist of three fundamental subatomic particles:
● Protons (+ charge, ~1 amu)
● Neutrons (neutral, ~1 amu)
● Electrons (-charge,~1/1836 amu)
● Atomic Number (Z): Number of protons in the nucleus; defines the element.
● Mass Number (A): Total number of protons + neutrons.
● Isotopes: Atoms of the same element with different numbers of neutrons.
2. Historical Models of Atomic Structure :
Model Description Key limitations
Contribution
•Dalton's atom as a Atomic theory No internal
Model solid, based on structure
Indivisible elements
Sphere
•Thomson’s “Plum Discovery of No nucleus
, Model Pudding” electron
Electrons
embedded in
Positive sphere
•Rutherford Nucleus with Discovery of Could not
Model Protons, nucleus via explain
electrons gold foil electron
Orbiting experiment stability
nucleus
•Bohr Electrons orbit Explanation of only works
Model nucleus in hydrogen perfect for
fixed shells emission H atom
(quantized) spectra
•Quantum Electron Modern atomic Complex
Mechanical Probability theory mathematics
Model Clouds, involved
wavefunctions
(Schrödinger
equation)
3. Key Concepts in Quantum Atomic Structure
3.1 Wave-Particle Duality
•Electrons exhibit both particle and wave-like behavior.
•De Broglie wavelength:
λ= h/mv
Where h = plank's constant ,
m = mass ,
v = Velocity.
3.2 Heisenberg Uncertainty Principle:
• It is impossible to simultaneously know the exact position and momentum of an electron:
° { ∆x.∆p = ≥ h / 4π }
