Who proposed the planetary model of the atom?
Niels Bohr
Danish Physicist, 1885-1962
What does the Bohr model propose about the structure of the atom?
Atoms have a dense, centrally located nucleus with electrons in spherically shaped, well-defined orbits.
What is meant by ‘quantized’ energy levels?
Electrons exist in specific energy levels and can only move between these levels by absorbing or emitting energy.
What is a quantum?
A finite amount of energy required to move an electron from its present energy level to the next higher one.
How many electrons can the 1st energy level hold?
2 electrons.
How many electrons can the 2nd and 3rd energy levels hold?
8 electrons each.
What is a limitation of the Bohr model?
It does not account for the varying shapes of orbitals and inaccurately represents atoms in energy levels 4 and up.
What is the maximum number of electrons that the 4th and 5th orbitals can hold?
18 electrons.
What is the maximum number of electrons that the 6th and 7th orbitals can hold?
32 electrons.
What does the Quantum Mechanical Model describe?
The mathematical probability of finding an electron in a region of space around the nucleus.
Does the Quantum Mechanical Model accept that electrons follow exact paths?
No, it does not accept that electrons are limited to one exact path or orbit.
What is the principal quantum number?
Refers to the energy level or distance from the nucleus, represented by integers 1-7.
What shapes do the second quantum number refer to?
Shapes of orbitals: s, p, d, and f.
What is the spin quantum number?
Specifies the value for spin; electrons in the same orbital must spin in opposite directions.
What does the magnetic quantum number determine?
The orientation of the orbital in space in reference to other orbitals.
What is the shape of the ‘s’ sub-shell?
Spherical shape.
How many ‘p’ sub-shells are present per energy level?
Three ‘p’ sub-shells per energy level.
What is the maximum number of electrons in a ‘d’ sub-shell?
Ten electrons.
How many electrons can an ‘f’ sub-shell hold?
Fourteen electrons.
What are the three rules governing the order of filling electrons?
- Aufbau Principle
- Pauli Exclusion Principle
- Hund’s Rule
What does the Aufbau Principle state?
Electrons enter sub-shells of lowest energy first.
What does the Pauli Exclusion Principle state?
All atomic sub-shells contain a maximum of two electrons.
What does Hund’s Rule state?
When electrons occupy sub-shells of equal energy, one electron enters each sub-shell until all contain one electron.
What is electron configuration notation?
A representation that indicates the number of electrons in each energy level without specifying spin.
