3 (+1) Types of Chemical Bonds

There are 4 basic types of chemical bonds. These are; ionic, covalent, metallic and hydrogen bonds. Each has specific properties and involves specific “groups” of elements. The type of bond between 2 atoms depends on whether they both give or take electrons or if one atom gives electrons while the other takes electrons.

Ionic bonds: As implied by the name, these bonds involve ions. The result is called a salt. NaCl is a good example. Na being a group I element gives up one valence electron to a group VII element, the result is that the group I element gives up 1 electron, has a +1 charge (1+ oxidation state) emptying its outer shell and the group VII element gains 1 electron, has a -1 charge (1- oxidation state). The electrostatic charge attraction between these ions causes the solid to be strongly bonded but these salts are easily dissolved in water.

ionic bonds

Covalent bonds:

Metallic Bonds:

Metallic Bonds:
Video #1: Watch this video forst – it provides a good review of ionic and covalent bonding, the periodic table trends, electronegativity, and ionic bonding.

Video # 2: this video has a clear, pictorial explanation of metallic bonds.

Watch it and take notes – it will help you with your homework (pg 203 Assessment, and worksheet section 7.4 Metallic bonds and the properties of metals.

 

And now finally the extra “+1” bond, The Hydrogen Bond.  The Hydrogen bond is not strictly a molecular bond. Rather, it s a weak bond between molecules. The hydrogen bond is responsible for most of the amazing and unique properties of water, such as the fact that water boils at a higher temperature than alcohol, even though alcohol has a higher molecular weight.

Hydrogen Bonds:

The basic idea: Hydrogen has only one electron, so when it forms a covalent bond with a highly eletronegative atom such as Oxygen, the electron gets trapped (most of the time) in space between the Hydrogen and Oxygen atoms.  This means that the side of the hydrogen farthest from the Oxygen has less of an electron cloud shielding the nucleus (+ proton).  Then the far side of the Oxygen has extra electron cloud so it looks slightly positive.

 

HydrogenBond-1

The electrostatic attraction between the slightly negative side of the Oxygen and the positive side of the Hydrogen result in a very weak bond between the molecules.

 

For more  informqtion on bonding, please see the post on electronegativity.