Which statement best explains why hydrogen’s atomic number is equal to its mass?(1 point)
Responses
Hydrogen does not have any neutrons.
Hydrogen only has one electron
Hydrogen is in the first row and the first column of the periodic table.
Hydrogen is stable, with two electrons in its outer shell.
None of the given responses accurately explain why hydrogen's atomic number is equal to its mass number.
- "Hydrogen does not have any neutrons." - While it is true that the most common isotope of hydrogen (protium) does not have any neutrons, this statement does not explain why hydrogen's atomic number is equal to its atomic mass. The atomic number is defined as the number of protons in the nucleus, and the atomic mass is approximately the sum of the protons and neutrons. For hydrogen (protium), both the atomic number and atomic mass are approximately 1 because it has one proton and no neutrons.
- "Hydrogen only has one electron." - The number of electrons does not affect the atomic number or atomic mass directly. The atomic number corresponds to the number of protons in the nucleus, and the atomic mass is the sum of the protons and neutrons. Electrons have a negligible mass compared to protons and neutrons.
- "Hydrogen is in the first row and the first column of the periodic table." - The position of hydrogen in the periodic table does not directly explain the relationship between its atomic number and atomic mass. It simply indicates that hydrogen is the first element with one proton, which gives it an atomic number of 1.
- "Hydrogen is stable, with two electrons in its outer shell." - This statement is incorrect. Hydrogen is stable with only one electron, which is in its only shell (1s orbital). The stable electron configuration mentioned with two outer shell electrons applies to helium, not hydrogen.
The correct statement explaining why hydrogen's atomic number is equal to its atomic mass would be something like this:
"Hydrogen's atomic number is equal to its mass number because the most common isotope, protium, has one proton and no neutrons, giving it an atomic number of 1 and an atomic mass of approximately 1."
It's important to note that "mass number" is the sum of protons and neutrons in the atomic nucleus and is not the same as the "atomic mass" (or atomic weight), which is the weighted average mass of all the isotopes. However, in the case of the most common isotope of hydrogen, both the mass number and the atomic number are indeed 1.
what is the correct answer
The correct reason for hydrogen's atomic number being equal to its mass number for the most common isotope (protium) is:
"Hydrogen does not have any neutrons."
This statement directly addresses the fact that the atomic number is the number of protons in an atom's nucleus, which for hydrogen is 1, and that the mass number is the sum of protons and neutrons in the nucleus. Since the most common isotope of hydrogen, protium, has no neutrons, its mass number is also 1, making the atomic number and the mass number equal.
The correct response is: Hydrogen is in the first row and the first column of the periodic table.
Explanation: The atomic number of an element is the number of protons found in its nucleus. In the case of hydrogen, it has an atomic number of 1 because it has a single proton in its nucleus. The number of protons determines the identity of an element, so the atomic number of an element is unique to that element.
The atomic mass, on the other hand, takes into consideration both the mass of the protons and the mass of the neutrons in the nucleus. However, since hydrogen does not have any neutrons (in its most common form, called protium), its atomic mass is roughly equal to its atomic number.
Options like "Hydrogen only has one electron" and "Hydrogen is stable, with two electrons in its outer shell" are incorrect as they pertain to the electron configuration of hydrogen, which is not related to its atomic number or mass.