Today we'll be going over the differences between ionic and covalent bonds. The type of bond formed depends on the electronegativity of the element, that is, the attraction the element has for an electron, and the fact that the most stable arrangement of electrons around atoms has eight electrons, known as an octet. Covalent bonds are bonds where two atoms share two a pair of valence electrons. Covalent bonds usually occur between non-metals that are either of the same element, or of elements close to each other on the Periodic Table. There are two types of covalent bonds. If the difference of the electronegativities of the two elements is very small, less than 0.5, then the bond is most likely a non-polar covalent bond. The two atoms share some electrons so each atom is surrounded by eight electrons, and the shared electrons spend an equal amount time around each atom. If the electronegativity difference is more than 0.5, but less than 1.7, then the bond is most likely a polar covalent bond. Polar covalent bonds occur when elements share electrons unequally. The electrons are more strongly attracted to the atom with greater electronegativity, and spend more time closer to that atom. Ionic bonds form primarily between metals and non-metals. The electronegativity of metals is much smaller than that of non-metals, so the electronegativity difference is greater than 1.7. Non-metals will remove valence electrons from metals. This results in a positively charged metal cation and a negatively charged non-metal anion, both surrounded by on octet of electrons. The two oppositely charged ions attract each other and form a bond. You can predict the type of bond that forms between elements by calculating the electronegativity difference using and electronegativity chart.Thank you for watching. For more information, please visit About.com.