A sodium atom has 11 protons, 11 neutrons and 11 electrons. If the atom loses one electron, what is the resulting particle?
A A different element
B A different isotope
C A differention
D A different atomic number
E A different molecule
The correct answer and explanation is :
The correct answer is C: A different ion.
Explanation:
When a sodium (Na) atom loses one electron, it forms a positively charged ion called a cation. Sodium has an atomic number of 11, meaning it has 11 protons and 11 electrons when it is neutral. The number of protons in an atom determines the element’s identity, so by losing an electron, the sodium atom does not change its identity as sodium. However, the loss of an electron changes the electrical charge of the atom.
An ion is a charged particle that results from the loss or gain of electrons. In this case, when the sodium atom loses one electron, it loses a negatively charged particle, leaving behind an excess of positive charge. This results in a Na⁺ ion (sodium ion), where the positive charge indicates that there is one more proton than electrons. Since the number of protons stays the same, the element remains sodium.
The other answer choices are incorrect for the following reasons:
- A: A different element: The loss or gain of an electron does not change the identity of the element, which is determined by the number of protons. Since sodium still has 11 protons, it remains a sodium atom.
- B: A different isotope: Isotopes are different forms of the same element with varying numbers of neutrons, not electrons. Losing an electron does not affect the number of neutrons, so this is not a different isotope.
- D: A different atomic number: The atomic number is defined by the number of protons in an atom, which does not change when an electron is lost.
- E: A different molecule: A molecule is a chemical combination of atoms, and losing an electron does not change the composition of atoms in a molecule, it only affects the atom itself.
Therefore, when a sodium atom loses one electron, it forms a Na⁺ ion and becomes a different ion, not a different element, isotope, atomic number, or molecule.