The+Properties+of+Water

H2O is held together by covalent bonds, as the O atom shares one electron with each of the two H atoms, and the H atoms each share one electron with the O atom. But the O atom is more electronegative because it has more electron shells than the H atoms. Electronegativity is an atom's attraction to an electron. In a non-polar covalent bond, the electronegativity of the atoms in the bond is the same for all the atoms. In a polar covalent bond, one or more atoms have a stronger pull on the electrons than the other atom(s). Water is a polar covalent bond. As the O atom pulls the electrons toward itself from the H atoms, it becomes partially negatively charged, while the H atoms become partially positively charged. All of water's properties are based off of it's polarity. The first property, hydrogen bonding, is fairly simple. Because the O is partially positive, it attracts to other water molecules' H atoms, and vice versa. Each molecule can bond with four other molecules using this bond. This bond is not a not a very strong bond, and is not chemical. Because of water's H bonds, this makes all water molecules want to stick together, called cohesion. This is what makes it possible for trees to suck water up from their roots, against gravity. Also from water's cohesion comes its surface tension. This is caused because the molecules on the top of the water are bonding with less than four other molecules (since there aren't any on the top), thus the remaining bonds are stronger. Because of this, surface tension occurs, and objects denser than water can still "float" on the surface because they aren't heavy enough to break the surface (such as water striders). Water's third property is that it moderates temperature. Water takes more heat to raise its temperature, because it takes more heat for the H bonds to break. Heat is a measure of the energy associated with the movement of atoms in a body of matter. Because of H bonds, water molecules don't want to move as much, thus it takes a lot of heat to break the bonds, move the atoms and raise the temperature. As water cools down, on the other hand, the H bonds form again, and this releases heat, slowing the process of cooling down. A fourth property of water is that ice is less dense than liquid water. This is because in liquid water, H bonds last very shortly, thus the atoms can be closer together when there aren't any bonds. On the other hand, in ice, the bonds are always present, and the molecules stay a further distance apart, giving ice more volume, thus less density. In simpler words because ice a solid it has a much more structured shape than water which allows for air to penetrate in between the H bonds air is less dense than water otherwise water would float on top of the air instead of the other way around, which is why ice floats on top of the water. Its volume is mostly comprised of air while waters is mostly comprised of water molecules. This is very important, because if ice sank in water, eventually all our bodies of water would freeze over because they wouldn't have time to thaw out on the surface. A fifth property of water is that water is a versatile solvent. Many substances will dissolve in water because its atoms attract to the H bonds as well, and it pulls the substance apart.