Final answer:
B. 4 valence electrons. A carbon atom can bond to 4 other atoms due to having 4 valence electrons, which allows it to form up to four covalent bonds to fulfill the octet rule, as seen in compounds like methane and carbon dioxide.
Step-by-step explanation:
A carbon atom can bond to 4 other atoms because it has 4 valence electrons. In an atom of carbon, which has an atomic number of 6, the first two electrons fill the inner shell, and the remaining four are in the second shell. These four valence electrons are available for forming covalent bonds, allowing carbon to achieve a stable electron configuration, or octet, by sharing electrons with other atoms.
For example, in the methane molecule, CH4, carbon forms four single covalent bonds with four hydrogen atoms. Another example is carbon dioxide (O=C=O), where carbon forms two double covalent bonds with two oxygen atoms, each share sharing two pairs of electrons. These bonding capabilities illustrate how carbon satisfies the octet rule via covalent bonding.
Individual carbon atoms have an incomplete outermost electron shell. With an atomic number of 6 (six electrons and six protons), the first two electrons fill the inner shell, leaving four in the second shell. Therefore, carbon atoms can form up to four covalent bonds with other atoms to satisfy the octet rule. The methane molecule provides an example: it has the chemical formula CH4. Each of its four hydrogen atoms forms a single covalent bond with the carbon atom by sharing a pair of electrons. This results in a filled outermost shell.