Lesson 2 Flashcards
Atomic theory and flaws
The Atomic theory allowed only a limited description of electrons in atoms up to atomic number 20.
The four quantum numbers improve the theoretical description to include all atoms on the periodic table and improves the explanation of chemical properties.
History of atomic theory
Historical atomic theory 🡪 based on the idea of an electron traveling in some kind of orbit or path
Modern version 🡪 _electron orbital 🡪 a region of space around the nucleus where the electron is most likely to be found
How is an electron represented in terms of spin?
An arrow, pointed up or down
What does an upright arrow represent in electron spin?
ms = +1/2
What does an upside-down arrow represent in electron spin?
ms = -1/2
First arrow drawn should be…
Up! fill all boxes with up arrows, then fill up downwards arrows
What is the Pauli Exclusion Principle?
No two electrons in an atom can have the same four quantum numbers.
How does the Pauli Exclusion Principle apply to electrons in the same atomic orbital?
No two electrons in the same atomic orbital can have the same spin; only two electrons with opposite spins can occupy any one orbital.
What is the Aufbau Principle?
Each electron is added to the lowest energy orbital available in an atom or ion before filling a higher energy orbital.
What does the Aufbau Principle determine?
The specific order of filling orbitals in an atom or ion.
What is the Hund’s Rule?
One electron occupies each of several orbitals at the same energy with a positive spin (ms = +1/2) before a second electron can occupy the same orbital with a negative spin (ms = -1/2).
How are electrons distributed according to Hund’s Rule?
Spread out the electrons with a positive spin as much as possible horizontally in a subshell before doubling up with an electron with a negative spin.
What is a condensed electron configuration?
It involves using the noble gas that precedes the element and then continuing to write the remaining electrons in their orbitals.
Can a noble gas be its own condensed electron configuration?
No, a noble gas cannot be its own condensed electron configuration.
Quantum #s and electron configuration
each electron in an atom has its own unique set of four quantum numbers.
Compare the quantum numbers that distinguish a ground state hydrogen atom from a helium atom.
