Video Transcript
The following figure describes an
atom of hydrogen and helium. Which statement makes a valid
comparison between these different atom types? (A) The helium atom has a lower
atomic number than the hydrogen atom. (B) The helium atom has fewer
protons than the hydrogen atom. (C) The hydrogen atom has a higher
mass number than the helium atom. (D) The helium atom has more
protons than the hydrogen atom. (E) The helium atom has fewer
neutrons than the hydrogen atom.
To answer this question, we need to
compare the hydrogen atom on the left to the helium atom on the right. To do this, we need to know what
the numbers in this notation mean. The number written to the bottom
left is the atomic number. The atomic number represents the
number of protons in an atom. The number written to the top left
is the mass number. The mass number is equal to the
number of protons plus the number of neutrons in an atom. We can use this equation to
determine the number of neutrons in each of the atoms given.
The hydrogen atom has a mass number
of one and one proton. If we subtract one from both sides
of the equation, we find that the hydrogen atom has zero neutrons. The helium atom has a mass number
of four and two protons. If we subtract two from both sides
of the equation, we find that the helium atom contains two neutrons.
Now that we’ve looked at the figure
provided, we can evaluate each of the answer choices to determine which makes a
valid comparison between the different atom types.
Answer choice (A) compares the
atomic numbers of hydrogen and helium. As the helium atom has a higher
atomic number than the hydrogen atom, answer choice (A) is not a valid
comparison.
Answer choice (B) compares the
number of protons in each atom. As the helium atom has more protons
than the hydrogen atom, answer choice (B) is not a valid comparison.
Answer choice (C) compares the mass
numbers of each atom. As the hydrogen atom has a lower
mass number than the helium atom, answer choice (C) is not a valid comparison.
Answer choice (D) compares the
number of protons in each atom. The helium atom does have more
protons than the hydrogen atom. So, this statement is a valid
comparison and is likely the answer to the question. But just to be sure, let’s take a
look at answer choice (E).
Answer choice (E) compares the
number of neutrons in each atom. As the helium atom has more
neutrons than the hydrogen atom, answer choice (E) is not a valid comparison.
In conclusion, the statement that
makes a valid comparison between the hydrogen and helium atoms is answer choice
(D). The helium atom has more protons
than the hydrogen atom.
