alkanes-the structure and properties Flashcards
what bonds are in alkanes?
a type of covalent bond called a sigma bond
are sigma bonds full rotational ? why does it matter ?
yes so the carbons can rotate relative to each other
are covalent bonds strong ?why does it matter?
ye and it takes a lot of energy to break
when do sigma bonds form ?
when electron orbitals from adjacent atoms overlap
what does a sigma bond contain?
a pair of electrons - one from each atom on wither side of the bond .
where do the electrons lie in a sigma bond ?
directly between the bonding atoms
what do covalent bonds around each carbon form ?
tetrahedral structure
what bond angles do covalent bonds around carbon atoms have ?
109.5
what type of molecule are alkanes ?
saturated hydrocarbons
what is the general formula of alkanes?
CnH2n+2
decribe and explain the electronegativity in alkane?
carbon and hydrogen have very similar electronegativity so essentially non polar
why cant alkanes be soluble in water?
water molecules have hydrogen bonds with eachother but alkanes have no permanent dipoles so can’t form hydrogen bonds
explain and describe alkanes reactivity ?
generally unreactive (only react under certain conditions ) .This is due to strong covalent bond within alkanes
what two circumstances increases boiling point of alkanes ?
longer carbon chain .
straight chain alkanes
why does boiling point increase with length of carbon chain ?
intermolecular forces in alkanes mean their non polar polar molecules so the london forces acting between alkanes are induced dipole dipole interactions .london forces don’t take alot of energy to break but as but as length increases so does strength of london forces .this is becauses longer chain alkanes have more electrons .
longer alkanes also have more surface area so their are more points to form London forces.
