How convert word to bit array?

Please how convert word to 16 bit array?

Treat it that way. A word is a 16-bit array, you just can't use the a[i] syntax on it.

The arduino provides a number of handy bit setting functions just for this kind of thing.

check - -

#define bitRead(value, bit) (((value) >> (bit)) & 0x01)
#define bitSet(value, bit) ((value) |= (1UL << (bit)))
#define bitClear(value, bit) ((value) &= ~(1UL << (bit)))
#define bitWrite(value, bit, bitvalue) (bitvalue ? bitSet(value, bit) : bitClear(value, bit))

as the consts used are UL (unsigned long) this code even works for 32 bits version.