List two differences between a compound and a mixture.

Chemical bonding is the process by which atoms combine to form compounds. In a compound, atoms are held together by strong chemical bonds. These bonds can be covalent, ionic, or metallic depending on the elements involved. For instance, in water (H₂O), the hydrogen and oxygen atoms are bonded covalently. In an ionic compound like sodium chloride (NaCl), sodium and chloride ions are bonded together through ionic bonds.
Unlike compounds, mixtures consist of different substances that are physically combined. No chemical bonds are formed between the components in a mixture, hence they retain their own chemical properties.

Separation methods help to distinguish between compounds and mixtures. In compounds, the elements are chemically bonded in a fixed ratio and cannot be separated by physical means. They require chemical reactions to break the bonds and separate the elements.
On the other hand, mixtures can be separated using various physical methods, including:

• Filtration: Separates solids from liquids in heterogeneous mixtures.
• Distillation: Separates liquids based on differences in boiling points.
• Evaporation: Removes a liquid from a solution to leave the solute behind.
• Magnetism: Removes magnetic materials from a mixture.

This shows that mixtures are easier to separate than compounds as they do not require chemical reactions for separation.

In compounds, elements combine in a definite and fixed ratio. This means that the chemical formula of a compound always represents the same ratio of elements. For example, water (H₂O) always contains two hydrogen atoms for every one oxygen atom.
This fixed ratio is a key difference between compounds and mixtures. In mixtures, the proportion of components can vary; there is no fixed ratio. You can have different amounts of the substances mixed together, such as adding more sugar to water to get a sweeter solution. However, changing the ratio in a compound means creating a different compound altogether.
This concept is fundamental in understanding why compounds are pure substances with specific properties, while mixtures can vary widely in their composition and properties.