Baby/toddler food question. 

I'm having a real problem with my baby not chewing food. He is nearly 13 months now. I've always given him spoon food and finger food but always cut up the finger food small. He just can't get the hang of chewing. I've tried big cucumber, bigger sandwiches, long bits of banana cut into quarters (Long ways) which he choked on for ages this morning and it was really scary- I had to smack his back, also tried those organix puff things. Nothing works. He just swallows whole. Is this normal?! At Easter when he had a chocolate button he swallowed that whole too. Don't know what to do!! X