5) Electrons and bonding Flashcards
Energy increases as shell number _?
increases
Define principal quantum number n
a number representing the relative overall energy of each orbital, which increases with distance from the nucleus
What are the sets of orbitals with the same n-value referred to as?
electron shells or energy levels
Define atomic orbital
a region around the nucleus that can hold up to 2 e-, with opposite spins
Describe a s-orbital
spherical shape
as n increases, radius increases
Describe a p-orbital
dumb-bell shape
as n increases, reaches further away from the nucleus
Define sub-shell
a group of orbitals of the same type within a shell
Describe the filling of orbitals
orbitals fill in order of increasing energy
electrons pair with opposite spins
orbitals with the same energy are occupied singly first (bus-seating rule)
What is special about the 3d sub-shell?
it is at a higher energy level than the 4s sub-shell so it is filled after and emptied after the 4s sub-shell
What does electron pairing with opposite spins help to do?
counteract the repulsion between the negative charges of the 2 electrons
When orbitals with the same energy are occupied singly first (bus-seating rule), what does it prevent?
any repulsion between paired electrons until there is no further orbital available at the same energy level
Define electron configuration
a shorthand representation that shows how electrons occupy sub-shells in an atom
In an electron configuration, how are shells listed?
in shell order rather than in order of filing
How can electron configurations be expressed more simply?
in terms of previous noble gas plus outer electron sub shells
When are positive ions / cations formed?
when atoms lose electrons
When are negative ions / anions formed?
when atoms gain electrons
Define ionic bonding
the electrostatic attraction between positive and negative ions
In ionic bonding electrons are _ whereas, in covalent bonding electrons are _?
transferred
shared