Compounds have different properties from the elements that make them. The atoms of different elements are held together in compounds by chemical bonds. Chemical bonds can hold atoms together in large networks or in small groups. Bonds help determine the properties of a compound.

Reasons for Different Properties of Compounds:
- Chemical Composition: The properties of compounds are primarily determined by their chemical composition. Each compound is made up of specific elements in fixed ratios, which contribute to their unique characteristics.
- Arrangement of Atoms: The arrangement of atoms within a compound plays a crucial role in defining its properties. The way atoms are bonded together (ionic, covalent, metallic) affects various properties such as melting point, boiling point, and solubility.
- Intermolecular Forces: Intermolecular forces (e.g., hydrogen bonding, dipole-dipole interactions, van der Waals forces) between molecules also influence the properties of compounds. Stronger intermolecular forces result in higher boiling points and lower vapor pressure.
- Crystal Structure: The crystal structure of a compound determines its physical properties like shape, hardness, and conductivity. Different arrangements of atoms in crystals lead to variations in properties such as transparency and brittleness.
- Electron Configuration: The electron configuration of elements in a compound affects its reactivity and chemical behavior. Elements with similar electron configurations tend to exhibit similar properties.
- Functional Groups: In organic compounds, functional groups such as hydroxyl (-OH) or carbonyl (C=O) impart specific properties to the compound. The presence of different functional groups leads to diverse chemical and physical characteristics.
In conclusion, the unique combination of chemical composition, atomic arrangement, intermolecular forces, crystal structure, electron configuration, and functional groups contribute to the distinct properties observed in different compounds. Understanding these factors is essential in predicting and explaining the behavior of various substances in the world of chemistry.