Water is a chemical substance or molecule that is formed by the union of an oxygen atom (O) with two hydrogen atoms (H). These three atoms are held together by the formation of covalent bonds, very strong and stable bonds. The water molecule has the formula H20, which can be written as HOH. It is this molecule, its bonds and their interactions that are responsible for making it a colorless and tasteless liquid substance. Water is found in a large proportion distributed throughout the Earth, between fresh and salt water. Water is essential for life to exist on our planet, as it is a very valuable natural resource. It is found between 60 to 70% in living organisms, which is a high proportion that allows them to fulfill innumerable functions. Among some of these vital functions are the structural ones, the regulators such as the maintenance of body temperature and the regulation of pH (acidity or vvvvvvvvvvvvvvvvvvvvvvvvvv) within normal limits. Likewise, water carries out the transport of nutrients and waste in living beings. It is also used in many areas of the productive, technological, scientific and daily routine of human beings; from cleaning, cooking food, among other uses. In this video I will explain the physical and chemical properties of water. And if you want to learn more about this and other topics, you can visit the description link at lifeder.com Physical properties of water The physical properties of water are related to the characteristics or magnitudes that can be measured or determined by considering matter, such as example its mass, energy, among others. Among the physical magnitudes of water are its color, smell, the forms in which it can be found, and all those that we can determine without producing reactions or altering its chemical composition. Taste When tasting a little pure water to our palate we can notice that it has no flavor. It is also odorless or odorless. Due to the purification process, you can sometimes perceive a slight odor due to chlorine residues. It is the minerals that give the water different flavor cards. Appearance Water is generally colorless and transparent when viewed in a glass. However , it appears to have a slightly light blue color when it accumulates in large quantities in large containers, or when observed in glaciers, rivers, or seas. And it is that in fact, the water exhibits a certain pale bluish coloration, whose perception is concentrated the greater the amount of water. States of water Water is very abundant on Earth and can be found in any of three states of matter: solid, liquid or gas. Water at room temperature is a liquid substance, which corresponds to its most common form. As a solid, water is called ice or snow, depending on the size of its crystals and the process of its formation. Meanwhile, the gaseous state is formed when the water changes from a liquid to a gaseous state, forming the famous water vapour, easily recognizable in the kitchen and on top of food. Density The density of pure water is around 1 gram per cubic centimeter. Meanwhile, the density of seawater is slightly higher due to the salt it contains. Freezing point Water freezes at 0 °C. At this temperature it passes from its liquid phase to its solid phase. As water freezes, it expands. That is why in its solid form it has less density than in its liquid state, which makes it easier for ice to float on liquid water. Also, this is the reason why when the water in a bottle cools, it should not be filled too much, since the ice expands and ends up breaking the bottle. Boiling point Water has a high boiling point which is 100 °C. It must be subjected to a lot of heat so that it can heat up and boil or reach its boiling point. The water then has a high specific heat, or also called heat capacity, which makes it take time to heat up; but also in cooling, that is, the process required for it to lose the acquired heat is slow. This property makes it very useful in refrigeration systems, in body temperature regulation systems, among other related ones. Electrical conductivity Water is a good conductor of electricity. No matter how pure the water is, it will always have some amount of ions, which gives it the property of having one of the highest dielectric constants among non-metallic liquids. Cohesion Water molecules are held together by so-called hydrogen bonds: weak bonds established between one water molecule and another. Due to this high level of cohesion it is very difficult to compress the water. Adhesion It is easy for water to adhere, for example, to a very clean glass surface, forming a film, which we call humidity or “wet”. Also, water adheres quickly to our skin, which is why we get wet as soon as it rains or we get into a pool. Otherwise, we would be dry in seconds. Surface tension Surface tension is the resistance offered by the liquid on its surface to be penetrated. Water has a high surface tension, product of the cohesion that exists between its molecules, which makes it easily form drops, instead of spreading freely on a smooth surface. Surface tension is evidenced when insects appear to move or walk on water without sinking, and is the reason why some leaves or other light objects can float on water. Capillarity The ease with which water moves up or down a capillary tube describes the capillary property of water. This property is also due to the high cohesion and adhesion properties of water. Capillarity is used by plant nature to supply water to the leaves of the highest branches of a tree, as well as facilitating its absorption by plant roots. Likewise, the properties of surface tension and capillarity make the water a structural part of the cells, that it forms part of the blood, and that it runs or flows easily through the different blood vessels. Solvent action Water can dissolve many substances, which is vital for living organisms, since all chemical reactions of living beings take place in an aqueous medium. In living organisms it serves as a transport for nutrients, ions and many other substances. It also serves to transport waste, such as urea, which is eliminated in the urine water. When a substance dissolves and mixes well with water, it is said to be hydrophilic or water-soluble. If it does not mix or dissolve well, the substance is said to be hydrophobic or insoluble in water. Chemical properties of water Chemical properties or characteristics are those that occur when changes occur in the chemical structure of water. It is important then to take a brief look at its molecular structure. Chemical nature Water is an inorganic molecule, because it does not contain C (carbon), and its chemical formula is H20. Its atoms come together by sharing electrons, forming covalent bonds, strong and very stable bonds. Its molar mass is 18 g/mol, that is, one mole of water has a mass of 18 grams. Polarity The water molecule is neutral, but it has a certain polarity, due to the fact that the sharing of its electrons is not so equitable. As the oxygen more strongly attracts the shared electrons towards itself, the water molecule is left with this side where the oxygen is with a tendency to have a certain negative charge; and therefore, it remains with a partial positive charge towards where the hydrogens are (see the image above). This polarity facilitates the union of water molecules with each other and the union of water with other molecules that also have differences in charge in their structure, which promotes the physical properties described in the previous sections. Ionization Spontaneously in liquid water, slight ionization or self-dissociation occurs. It means that some of its molecules rearrange themselves, changing their normal molecular structure, generating new electrically charged molecules, such as hydronium and hydroxyl ions. Reactive capacity Water reacts with many substances, forming a wide variety of chemical compounds. By electrolysis water can be broken down by separating oxygen from its two hydrogens. This process occurs when an electric current passes through the water. Even water in its solid form can also take part in some chemical reactions. pH Pure water has a neutral pH (equal to 7), while seawater is slightly alkaline (greater than 7). Rainwater becomes slightly acidic (pH less than 7) when mixed with components found in the atmosphere, such as carbon dioxide or C02, for example. Amphoterism Water is amphoteric, that is, it can behave as an acid or a base depending on the pH of the solution. This chemical property supports its role as a pH regulator.