KA1: Molecular orbitals Flashcards
what theory can provide an explanation for bonding in more complex molecules?
molecular orbital theory
when do molecular orbitals form?
when atomic orbitals combine
the no. of molecular orbitals formed=
the no. of atomic orbitals that combine
what does the combination of two atomic orbitals result in?
bonding molecular orbital and an antibonding orbital
what does the bonding molecular orbital encompass?
both nuclei
what is the basis of bonding between atoms?
the attraction of the positively charged nuclei and the negatively charged electrons in the bonding molecular orbital
what is the max no. of electrons that each molecular orbital can hold?
2
describe the bonding molecular orbital in a non-polar covalent bond
symmetrical about the midpoint between two atoms
what do polar covalent bonds result from?
bonding molecular orbitals that are asymmetric about the midpoint between two atoms
the atom with the greater value for electronegativity has…
the greater share of bonding electrons
what are ionic compounds an extreme case of?
asymmetry
the bonding molecular orbitals almost entirely located around just one atom=resulting in the formation of ions
what are sigma (σ) molecular orbitals or sigma bonds?
orbitals bond end-on
what are pi (π) molecular orbitals or pi bonds?
orbitals bond side-on
what does the electronic configuration of an isolated carbon atom not explain?
the number of bonds formed by carbon atoms in molecules
what does hybridisation explain?
the bonding and shape of molecules of carbon
what is hybridisation?
the process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals
these hybrid orbitals are degenerate
in alkanes, what do the 2s orbital and the three 2p orbitals of carbon hybridise to form?
four degenerate sp3 hybrid orbitals
what arrangement do the four sp3 hydrid orbitals adopt?
tetrahydral
what do the sp3 hybrid orbitals form and how to they do this?
-σ bonds
-overlap end-on with other atomic orbitals
what can the bonding alkenes be described in terms of?
sp2 hydrisation
when are three degenerate sp2 hybrid orbitals formed?
when the 2s orbital and two of the 2p orbitals hybridise
what arrangement do the sp2 orbitlas adopt?
trigonal planar
how do the hybrid sp2 orbitals overlap to form σ bonds?
end-on
what happens to the remaining 2p orbital on each carbon atom on the double bond?
its unhybridised and lie perpendicular to the axis of the σ bond
the unhydridised p orbitals overlap side-on to form π bonds
