Final answer:
A functional group imparts specific chemical properties to a molecule, acting as a reactive site. Its consistent behavior across various molecules allows chemists to classify and predict reactions within organic compounds. Electronegativity and the presence of specific atoms such as oxygen or nitrogen within functional groups can enhance molecular reactivity.
Step-by-step explanation:
The presence of a functional group causes a molecule to become reactive because it acts as a site for chemical reactions to occur. A functional group is a specific grouping of atoms within a molecule that imparts consistent chemical properties to the molecule, regardless of the other atoms or functional groups present.
These groups can include different atoms such as oxygen, nitrogen, or chlorine, and they exhibit characteristic reactivity when they occur in different compounds.
Functional groups determine the chemical reactivity of an organic molecule under varying conditions. Major families of organic compounds, like alcohols and ketones, are characterized by their functional groups which can affect the molecule's polarity and the distribution of electrons. For example, the carbonyl group can undergo resonance, contributing to the heightened reactivity of molecules like aldehydes and ketones.
Electronegativity plays a significant role in the reactivity of functional groups, particularly when a carbon atom is bonded to a more electronegative atom. This results in a partial positive charge on the carbon, influencing the molecule's ability to participate in chemical reactions. Hence, understanding functional groups helps chemists classify and predict the reactivity of organic molecules.