Valence and Core Electrons Flashcards
What are valence electrons and why are they important?
Electrons in the outermost shell (the highest n/highest energy), they are important because they are exposed to other atoms when they react. Valence electrons have the highest energy and are “active”
What is unique about the d-block elements valence electrons?
4s and 3d orbitals play an important role. Valence electrons are present in the outermost s shell and the d shell just below as well.
Why is the electronic configuration in the orbital box diagram of chromium and copper different?
Instead of the 4s orbital having two electrons, one is given to the 3d orbital; and then the 4s and 3d orbitals become degenerate at ground state in CHROMIUM. For both Chromium and Copper, this is because half-filled orbitals are energetically more stable.
What are core electrons?
Also known as inner shell electrons, they are buried deep in the atom and don’t play an important role in chemical reactions
What are ions?
An atom with a positive or negative charge because electrons are transferred (either gained or lost from their valence shell)
What is a cation?
Ions with a positive charge, generated when an atom loses electrons
What is an anion?
Ions with a negative charge, generated when an atom gains electrons
What is the most stable configuration for an ion?
Isoelectronic configuration: same number of electrons as a noble gas. It is most stable when it has an electronic configuration like a noble gas. A filled subshell is also favoured to make it more stable.
Where are electrons first lost?
The shell with the highest n value.
What is the octet rule?
Atoms lose or gain electrons to achieve the electron configuration of the nearest noble gas, which as 8 electrons in its valence shell. However this rule is not always obeyed (Fe 2+ and 3+)
What is a cation charge?
Conveyed in roman numerals; it is the amount of electrons removed from the valence shell
