Final answer:
Potassium (K) isotopes, such as K-41, differ from the neutral potassium atom in the number of neutrons within the nucleus. Neutral potassium atoms contain an equal number of protons and electrons. An isotope such as K-41 has 22 neutrons while maintaining the same number of protons (19) common to all potassium atoms.
Step-by-step explanation:
The term isotope refers to atoms of the same element that have different numbers of neutrons in their nuclei but the same number of protons. Potassium (K), with an atomic number of 19, has isotopes that differ in their neutron count. The most common isotope, potassium-39, has 20 neutrons, while potassium-40, an isotope that is also naturally occurring but in smaller amounts, has 21 neutrons. The extra neutron in potassium-40 gives it a different mass and slightly different properties compared to the more abundant potassium-39.
Potassium is considered a neutral atom when it has an equal number of protons and electrons. Potassium-41 is an isotope of potassium because it has the same number of protons (19) as the other isotopes but a different number of neutrons (22). This is understood by knowing that the atomic number (which is 19 for potassium) indicates the number of protons, and the atomic mass number, minus the atomic number, gives the number of neutrons. For K-41, with an atomic mass number of 41, the number of neutrons would be 41-19=22 neutrons.
In its ionic form, potassium becomes a cation (K+), meaning it has lost an electron and carries a positive charge. This occurs because potassium has a single valence electron that it is more likely to donate during chemical reactions, for instance, to pair with sulfate ions to form potassium sulfate (K₂SO₄).
Remember, a neutral atom has an equal number of protons and electrons, whereas an isotope refers to variations in neutron count with an unchanged proton number. Each isotope of potassium has its own unique number of neutrons which is what classifies it as an isotope.