There are not exactly "five laws of chemical combination," but rather a set of fundamental principles that govern how elements combine to form compounds. Here are the key laws, often referred to as the Laws of Definite Proportions, Multiple Proportions, and Conservation of Mass:

1. Law of Conservation of Mass (Lavoisier, 1789): This law states that in a closed system, the total mass of the reactants before a chemical reaction is equal to the total mass of the products after the reaction. In simpler terms, matter cannot be created or destroyed in a chemical reaction, only transformed.

2. Law of Definite Proportions (Proust, 1799): This law states that a given chemical compound always contains the same elements in the same proportion by mass, regardless of its source or method of preparation. For example, water (H₂O) will always have a mass ratio of 1:8 (approximately) for hydrogen to oxygen, no matter where you find it.

3. Law of Multiple Proportions (Dalton, 1803): This law 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 element are simple whole numbers. For example, carbon and oxygen form two common oxides: carbon monoxide (CO) and carbon dioxide (CO₂). The ratio of oxygen to carbon in carbon dioxide is twice that in carbon monoxide.

4. Law of Reciprocal Proportions (Richter, 1792): This law states that if two elements combine separately with a fixed mass of a third element, then the ratio of their masses in which they combine with each other is either the same or a simple multiple of the ratio in which they combine with the third element. This can be seen as a more specific application of the Law of Multiple Proportions.

5. Gay-Lussac's Law of Combining Volumes (Gay-Lussac, 1808): This law applies to gases and states that when gases react, they do so in volumes that are simple whole-number ratios, assuming the gases are at the same temperature and pressure. This law, alongside Avogadro's hypothesis, led to the understanding that gases are composed of molecules.

These laws, along with the later development of atomic theory, laid the foundation for our understanding of how matter is structured and how chemical reactions occur. They are still essential for understanding the composition and properties of chemical compounds.