If electrons move with very high speed in shells,then how electrons participate in chemical bonding.
Electrons do not...
Electron is nothing but a cloud, somewhere its density is more and somewhere it is less.
Its density changes continuosly wrt position in atom.
When high density cloud of two different atom come in contact, they form bond.
Denser clouds contact forms stronger bond.
Speed is not concerned
And electrons of last orbital take part in chemical bonding due to shelding effect as attractive force decreases
Due to attractive force offered by more electronegative element with respect to other