Here's why:
* Atomic Number: The number of protons in an atom's nucleus defines its atomic number. Hydrogen has 1 proton, while oxygen has 8 protons.
* Protons and Neutrons: Protons and neutrons contribute significantly to an atom's mass. Since oxygen has more protons and usually more neutrons than hydrogen, it has a much greater mass.
Here's a rough comparison:
* Hydrogen Atom: 1 proton, typically no neutrons. Its mass is approximately 1 atomic mass unit (amu).
* Oxygen Atom: 8 protons, typically 8 neutrons. Its mass is approximately 16 atomic mass units (amu).
Key Point: The mass of an atom is primarily determined by the number of protons and neutrons it contains.
