Why is домой used as opposed to дом in the scentance "Я пойду домой"?

Question

I have decided to begin to learn Russian and came across a sentence that translates as *I'm going home *. However the literal translation in Russian is *I'm going homeward*. This raises the question would *Я пойду дом* be grammatically incorrect as opposed to the sentence written in the question? If the sentence is grammatically incorrect why ? Does the verb *to go* modify the noun in some way?

Answer 1

Lyudmila is right: "домой" is an adverb of place, created from the noun "дом", the form is similar to Instr. case ending-like suffixes in "весной", "зимой".

Answer 2

домой is an adverb. It answers the question куда?.

дом is a noun. It answers the question что?.