It refers to the combining capacity of an atom but it specifies its charge.
A. oxidation number
B. valence electron
C. Avogadro’s number
D. molecular weight
The correct answer and explanation is :
The correct answer is A. oxidation number.
Explanation:
The term that refers to the combining capacity of an atom, but also specifies its charge, is the oxidation number (sometimes called oxidation state). This number represents the number of electrons an atom can gain, lose, or share when it forms a chemical bond with another atom. The oxidation number indicates the hypothetical charge that an atom would have if the compound were purely ionic, and it provides insight into the atom’s ability to form bonds, interact with other atoms, and undergo chemical reactions.
The concept of oxidation number is crucial in understanding redox reactions and molecular bonding.
In chemistry, oxidation and reduction processes (collectively known as redox reactions) are characterized by the transfer of electrons. The oxidation number helps to track the movement of electrons between elements in a reaction. An atom with a positive oxidation number has lost electrons (oxidized), while an atom with a negative oxidation number has gained electrons (reduced).
For example:
- In the compound H₂O (water), the oxidation number of hydrogen is +1, and the oxidation number of oxygen is -2. These numbers reflect the way the atoms in the compound have “shared” or “transferred” electrons.
- In ionic compounds, like NaCl (sodium chloride), the oxidation number of sodium is +1, and the oxidation number of chlorine is -1. This reflects the electron loss by sodium and electron gain by chlorine.
Why not the other options?
- B. Valence electron: This refers to the electrons in the outermost shell of an atom that participate in bonding. While valence electrons are important for bonding, they do not specify an atom’s charge in the same way the oxidation number does.
- C. Avogadro’s number: This is the number of particles (atoms, molecules, etc.) in one mole of a substance. It does not relate to an atom’s charge or combining capacity.
- D. Molecular weight: This is the sum of the atomic masses of the atoms in a molecule. While important for understanding the mass of a substance, it does not relate to the charge or combining capacity of individual atoms.
Thus, the oxidation number is the most accurate term that corresponds to the combining capacity and specifies the charge of an atom in a compound.