For question about parts of speech classified as particles.

Typically, particles are short words the do not fit well into the other parts of speech. They are used to express Tempus, Aspect, Modus, Polarity (TAMP) in many languages.

In English, the word not is calssified as a negation particle.

In Japanese, particles are small words (usually 1 or 2 syllables) that follow a word. Some are used to indicate that the preceeding word is the subject or object of a sentence.