90 likes | 277 Views
POLAR COVALENT BONDS ATOMS WITH SIMILAR ATTRACTIONS FOR ELECTRONS (ELECTRON AFFINITY) WILL SHARE ELECTRONS TO FORM COVALENT BONDS. THIS WOULD INCLUDE ELEMENTS CLOSE TOGETHER ON THE PERIODIC TABLE.
E N D
POLAR COVALENT BONDS ATOMS WITH SIMILAR ATTRACTIONS FOR ELECTRONS (ELECTRON AFFINITY) WILL SHARE ELECTRONS TO FORM COVALENT BONDS. THIS WOULD INCLUDE ELEMENTS CLOSE TOGETHER ON THE PERIODIC TABLE. LINUS PAULING, A NOBEL PRIZE WINNING CHEMIST, DEFINED A PROPERTY THAT HE CALLED ELECTRONEGATIVITY – THE ABILITY OF AN ATOM IN A BOND TO ATTRACT A SHARED PAIR OF ELECTRONS.
ATOMS WITH THE SAME OR SIMILAR ELECTRONEGATIVITIES WOULD FORM PURE COVALENT BONDS. • THE RULES ARE: • Non-polar bonds occur when the difference in electronegativity between the two atoms is less than 0.4 • Polar bonds occur when the difference in electronegativity between the two atoms is between 0.4 and 1.7 • Ionic bonds occur when the difference in electronegativity between the two atoms is greater than 1.7
FOR EXAMPLE, IF YOU HAD A BOND BETWEEN CARBON (EN = 2.55) AND HYDROGEN (EN = 2.2), THE DIFFERENCE IS 0.35, SO THE BOND WOULD BE COVALENT. IF YOU HAD A BOND BETWEEN HYDROGEN (EN=2.2) AND OXYGEN (EN = 3.44), THE DIFFERENCE IS 1.24, SO THE BOND IS POLAR COVALENT. IF YOU HAD A BOND BETWEEN SODIUM (EN = 0.93) AND CHLORINE (EN = 3.16), THE DIFFERENCE IS 2.23, SO THE BOND IS IONIC.
BONDS IN WATER ARE POLAR COVALENT. THESE GIVE WATER SOME VERY UNUSUAL PROPERTIES.