Element, Compound, Mixtures

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and gold (Au).

A compound is a substance formed when two or more elements chemically bond together in fixed proportions. Examples include water (H2O) and carbon dioxide (CO2).

A mixture is a combination of two or more substances that are not chemically bonded. Mixtures can be homogeneous (uniform composition) or heterogeneous (distinct phases).

A homogeneous mixture is a mixture that has a uniform composition throughout. An example is saltwater, where the salt is evenly dissolved in water.

A heterogeneous mixture is a mixture that has a non-uniform composition. An example is a salad, where the individual ingredients can be seen and separated.

A solution is a type of homogeneous mixture where one substance (the solute) is dissolved in another (the solvent). An example is sugar dissolved in water.

A pure substance has a constant composition and distinct properties, while a mixture contains two or more substances that retain their individual properties.

Mixtures can be separated by physical methods such as filtration, distillation, or chromatography, as the components retain their individual properties.

The law of definite proportions states that a chemical compound always contains its component elements in fixed ratio by mass.

The law of multiple proportions states that when two elements form more than one compound, the ratios of the masses of one element that combine with a fixed mass of the other are in small whole numbers.