Iron is an important element in human body cells. If iron has an atomic number of 26, what does this tell you about this element?
a. An iron atom has 13 electrons and 13 protons.
b. An iron atom has 13 protons and 13 neutrons.
c. An iron atom is unable to become an isotope.
d. An iron atom has 26 protons.
The Correct Answer and Explanation is:
Correct Answer:
d. An iron atom has 26 protons.
Explanation:
The atomic number of an element is a fundamental property that identifies the element. It represents the number of protons in the nucleus of an atom of that element. Since the atomic number of iron is 26, it means every atom of iron has 26 protons in its nucleus.
Why Protons Are Important
Protons determine the element’s identity. For example:
- Hydrogen (atomic number 1) always has 1 proton.
- Oxygen (atomic number 8) always has 8 protons.
- Similarly, iron (atomic number 26) always has 26 protons.
This number is constant for all atoms of the element and does not change, even if the atom becomes an ion or an isotope.
Understanding the Other Choices:
- Choice a: Incorrect because it states an iron atom has 13 electrons and 13 protons, which adds up to 13 protons only. This does not match the atomic number of iron (26).
- Choice b: Incorrect because it suggests 13 protons and 13 neutrons, which also conflicts with the atomic number of iron. The number of neutrons in an iron atom can vary (leading to isotopes), but the protons must always be 26.
- Choice c: Incorrect because iron can indeed form isotopes. Isotopes are versions of an element with the same number of protons but different numbers of neutrons.
Electrons and Isotopes
In a neutral atom, the number of electrons equals the number of protons. For iron, a neutral atom has 26 electrons. If it gains or loses electrons, it becomes an ion. Regarding isotopes, iron can exist in forms such as Iron-56 or Iron-58, which have 30 and 32 neutrons respectively, while retaining 26 protons.
Thus, the atomic number 26 definitively means an iron atom has 26 protons in its nucleus.