conduction
conduction is the transfer of energy with no overall transfer of matter
convection is the transfer of thermal energy when particles of a fluid move from one place to another
RADIATION
radiation is the transfer of energy by waves moving through space
the reason conduction is slower in gases than in solides and liquids is because the particles in gas collide less often
daigram
this is a diagram of why the tempature is higher at the bottom of the oven