The main component of monosodium glutamate is sodium glutamate. The chemical formula of sodium glutamate is C5H7NO4Na2, so the substance consists of _ _ _ _ _ _ elements. One molecule of the substance. According to the chemical formula of sodium glutamate (C5H7NO4Na2), sodium glutamate is composed of five elements: carbon, hydrogen, nitrogen, oxygen and sodium. 1 molecule of sodium glutamate is composed of 5 carbon atoms, 7 hydrogen atoms, 1 nitrogen atoms, 4 oxygen atoms and 2 sodium atoms, so there are 19 atoms in one molecule of this substance; The mass ratio of carbon to nitrogen is (12× 5):14 = 30: 7.

So the answer is: 5; 19； 30：7．