The area around the oxygen is somewhat negative compared to the opposite, hydrogen-containing end of the molecule, which is slightly positive. Opposites attract, so this lopsided charge difference allows bonds to form between the hydrogen and oxygen atoms of adjacent H 2 O molecules. Each H 2 O can bind to a maximum of four neighbors through these so-called hydrogen bonds. Main menu About this Site Table of Contents.
Types of Covalent Bonds: Polar and Nonpolar. In unit two, we compared atoms to puppies and electrons to bones in our analogy of how bonding works. Now one puppy has two electron bones and one puppy has none.
Because the electron bones in our analogy have a negative charge, the puppy thief becomes negatively charged due to the additional bone. The puppy that lost its electron bone becomes positively charged. Because the puppy who lost his bone has the opposite charge of the thief puppy, the puppies are held together by electrostatic forces, just like sodium and chloride ions! In our analogy, each puppy again starts out with an electron bone. Some covalently bonded molecules, like chlorine gas Cl2 , equally share their electrons like two equally strong puppies each holding both bones.
Other covalently bonded molecules, like hydrogen fluoride gas HF , do not share electrons equally. The fluorine atom acts as a slightly stronger puppy that pulls a bit harder on the shared electrons see Fig. Even though the electrons in hydrogen fluoride are shared, the fluorine side of a water molecule pulls harder on the negatively charged shared electrons and becomes negatively charged.
The hydrogen atom has a slightly positively charge because it cannot hold as tightly to the negative electron bones. Covalent molecules with this type of uneven charge distribution are polar. Molecules with polar covalent bonds have a positive and negative side.
In this analogy, each puppy represents an atom and each bone represents an electron. Water H2O , like hydrogen fluoride HF , is a polar covalent molecule. When you look at a diagram of water see Fig. The unequal sharing of electrons between the atoms and the unsymmetrical shape of the molecule means that a water molecule has two poles - a positive charge on the hydrogen pole side and a negative charge on the oxygen pole side.
Explanation: The water molecule has H-O-H, 2 hydrogen and one oxygen present. Related questions What is intermolecular force? What are intermolecular forces? Why do biological systems need enzymes? Why do biological systems need water? How do intermolecular forces affect vapor pressure?
How do intermolecular forces affect viscosity?
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