Compare an electrically neutral atom of hydrogen and an isotope of hydrogen.

In comparison, a neutral hydrogen and an isotope of hydrogen have same chemical properties because o having the same number of protons and electrons, However, they have different number of neutrons which gives them their mass number. The difference in mass number gives the two isotope their mass related properties. For instance, a hydrogen isotope with an extra neutron will be much heavier than the neutral hydrogen.

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.