atomic structure Flashcards
What is atomic number? The number of protons in an atom
represented by Z.
What are isotopes?
Atoms of the same element with different numbers of neutrons.
What are isobars?
Atoms of different elements with the same mass number but different atomic numbers.
What are the fundamental particles of an atom?
neutrons & Protons
What was Rutherford’s gold foil experiment?
An experiment where alpha particles were directed at a thin gold foil to study atomic structure.
What were the conclusions of Rutherford’s experiment?
The atom has a dense positively charged nucleus
What is electromagnetic radiation?
A form of energy that travels in waves including light
What are the characteristic parameters of electromagnetic radiation?
Wavelength frequency
What is the relationship between wavelength and frequency?
Wavelength (λ) and frequency (ν) are inversely proportional: c = λν.
What is the hydrogen line spectrum?
A set of distinct lines observed in hydrogen’s emission spectrum.
What are Bohr’s postulates?
- Electrons orbit in fixed energy levels.
- Energy is absorbed/emitted when electrons move between levels.
- Angular momentum is quantized.
What is the energy level diagram of hydrogen?
A diagram showing electron transitions between energy levels forming spectral series like Lyman
Why are half-filled and fully filled orbitals stable?
Due to symmetrical distribution and exchange energy stabilization.
What is wave-particle duality?
The concept that matter and radiation exhibit both wave-like and particle-like properties.
What is Heisenberg’s uncertainty principle?
It is impossible to simultaneously determine the exact position and momentum of an electron.
Why is the quantum mechanical model needed?
It explains electron behavior using wave functions and probability distributions.
What are probability pictures of an electron?
Visual representations of electron cloud density showing where an electron is likely to be found.
What are quantum numbers?
Numbers that describe an electron’s energy shape
What is the significance of the principal quantum number (n)?
Indicates the energy level and size of the electron orbital.
What does the azimuthal quantum number (l) represent?
Defines the shape of the orbital (spfd)
What is the magnetic quantum number (mₗ)?
Determines the orientation of an orbital in space.
What does the spin quantum number (mₛ) indicate?
Specifies the spin of the electron (+½ or -½).
What are the shapes of s p d orbitals
s - spherical, p - dumbbell-shaped, d - complex clover-like.
What is a nodal plane?
A region in an orbital where the probability of finding an electron is zero.
What is Pauli’s exclusion principle?
No two electrons in an atom can have the same set of four quantum numbers.
What is the Aufbau principle?
Electrons fill orbitals starting from the lowest energy level.
What is Hund’s rule of maximum multiplicity?
Electrons fill degenerate orbitals singly before pairing up.
Why are half-filled and fully filled orbitals more stable?
They provide lower energy configurations due to exchange energy and symmetry.
How is atomic number related to chemical properties?
Elements with the same atomic number have the same number of protons and similar chemical properties.
What is the difference between isotopes and isobars?
Isotopes have the same atomic number but different mass numbers while isobars have the same mass number but different atomic numbers.
What did Rutherford’s experiment disprove?
It disproved the plum pudding model showing that atoms have a dense nucleus.
What was the major flaw in Rutherford’s model?
It could not explain why electrons do not spiral into the nucleus.
What is the speed of electromagnetic radiation in a vacuum?
3.0 × 10⁸ m/s.
What is Planck’s equation?
E = hν
where E is energy
What is the relation between energy and wavelength?
Energy is inversely proportional to wavelength: E = hc/λ.
What is the Rydberg formula for hydrogen spectra?
1/λ = R_H (1/n₁² - 1/n₂²)
where R_H is the Rydberg constant.
What are the spectral series of hydrogen?
Lyman (UV)
Balmer (visible)
Why does the hydrogen spectrum have discrete lines?
Energy levels are quantized so electrons absorb/emit photons of specific energies.
What are the limitations of Bohr’s model?
It only works well for hydrogen and does not explain multi-electron atoms.
How does the quantum mechanical model improve upon Bohr’s model?
It describes electron behavior as probability distributions rather than fixed orbits.
What is Schrödinger’s wave equation?
A mathematical equation describing the probability distribution of electrons in an atom.
What is an atomic orbital
? A region in space where an electron is most likely to be found.
How does probability relate to electron position in an atom?
The probability of finding an electron is given by the square of the wave function (ψ²).
What are the shapes of f orbitals?
f orbitals have complex shapes often resembling multi-lobed structures.
What is the total number of orbitals in a shell?
Determined by n²
where n is the principal quantum number.
What is the number of electrons that can be held in a shell?
Given by 2n²
where n is the principal quantum number.
What is an angular node?
A region where electron probability is zero due to orbital shape.
What is a radial node?
A spherical region around the nucleus where electron probability is zero.
How is the number of nodal planes in p orbitals determined?
p orbitals have one nodal plane.
How does Pauli’s exclusion principle influence electron configuration?
It ensures no two electrons in an atom have identical quantum numbers.
What is the order of filling of orbitals according to Aufbau principle?
Orbitals fill in increasing order of energy: 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p etc.
What is the significance of Hund’s rule?
It maximizes electron stability by keeping unpaired electrons in degenerate orbitals with parallel spins.
Why does Cr and Cu have unusual electron configurations? Due to extra stability of half-filled (Cr: 4s¹3d⁵) and fully filled (Cu: 4s¹3d¹⁰) d orbitals.
How does exchange energy contribute to orbital stability? Exchange energy stabilizes half-filled and fully filled orbitals by increasing parallel spin interactions.
