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Hydrogen Bonds Formation in Water
The theory of hydrogen bond formation in water
The molecular structure of water is H 2O O, and hydrogen and oxygen are connected by covalent bonds. The electron cloud of hydrogen atoms is biased towards the oxygen atom due to the strong electronegativity of the oxygen atom, resulting in a decrease in the density of the electron cloud outside the nucleus of the hydrogen atom, which is partially positively charged; the oxygen atom is partially negatively charged due to the electron cloud.
When a partially positively charged hydrogen atom of a water molecule is close to a partially negatively charged oxygen atom of another water molecule, electrostatic attraction occurs. The force of electrostatic attraction, that is, hydrogen bonding, is also. Although the force of hydrogen bonding is weaker than that of covalent bonds, it has a significant impact on the physical and chemical properties of water.
The formation of hydrogen bonds increases the interaction between water molecules, causing the boiling point of water to rise. If there is no hydrogen bond between water molecules, the boiling point of water should be much lower than the current 100 ° C in terms of relative molecular mass. And hydrogen bonds also affect the density of water. At 4 ° C, the arrangement of water molecules is most regular and tight due to hydrogen bonds, and the density is the largest; when the temperature rises and falls, hydrogen bonds are broken or rearranged, resulting in density changes.
From this perspective, the formation of hydrogen bonds in water stems from the difference in electronegativity of hydrogen and oxygen atoms in water molecules, which triggers electrostatic attraction. This is the key to understanding the unique properties of water.
The molecular structure of water is H 2O O, and hydrogen and oxygen are connected by covalent bonds. The electron cloud of hydrogen atoms is biased towards the oxygen atom due to the strong electronegativity of the oxygen atom, resulting in a decrease in the density of the electron cloud outside the nucleus of the hydrogen atom, which is partially positively charged; the oxygen atom is partially negatively charged due to the electron cloud.
When a partially positively charged hydrogen atom of a water molecule is close to a partially negatively charged oxygen atom of another water molecule, electrostatic attraction occurs. The force of electrostatic attraction, that is, hydrogen bonding, is also. Although the force of hydrogen bonding is weaker than that of covalent bonds, it has a significant impact on the physical and chemical properties of water.
The formation of hydrogen bonds increases the interaction between water molecules, causing the boiling point of water to rise. If there is no hydrogen bond between water molecules, the boiling point of water should be much lower than the current 100 ° C in terms of relative molecular mass. And hydrogen bonds also affect the density of water. At 4 ° C, the arrangement of water molecules is most regular and tight due to hydrogen bonds, and the density is the largest; when the temperature rises and falls, hydrogen bonds are broken or rearranged, resulting in density changes.
From this perspective, the formation of hydrogen bonds in water stems from the difference in electronegativity of hydrogen and oxygen atoms in water molecules, which triggers electrostatic attraction. This is the key to understanding the unique properties of water.
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