To slap with a flat object

One word substitute is Swat.

Hew: chop or cut (something, especially wood or coal) with an axe, pick, or other tool.
Swat: hit or crush (something, especially an insect) with a sharp blow from a flat object.
Chop: cut (something) into pieces with repeated sharp blows of an axe or knife.
Gnaw: bite at or nibble something persistently.