![]() The expected bond angle using atomic orbitals does not compare to the experimentally determined bond angle. Similar conflicts arise for ammonia and methane. (Remember the three p orbitals in a p subshell are all 90˚ from each other.) However, experimentally the H–O–H bond angle is actually 105˚, considerably larger. Using 2p orbitals on oxygen would result in a water molecule with an H–O–H bond angle of 90˚. There are two hydrogen atoms so we might try to describe each O–H in water using a 1s orbital on hydrogen and a 2p orbital on oxygen. In the case of water, H 2O ( see the movie), the oxygen atom has two 2p orbitals each with an unpaired electron. I(5p)–I(5p) Can we use atomic orbitals to describe the covalent bonds in other compounds? Problems Start Appearing If we try to use atomic orbitals to describe the covalent bonds in H 2OĬH 4 we run into some problems. We can describe the bond between the halogen atoms in the elements as F(2p)–F(2p) The covalent bond is formed along the internuclear axis between the two atoms. In each case the np orbital with one unpaired electron on the halogen overlap with the same np orbital on the other halogen. I 2 we can describe the covalent bond formed between the atoms using simple atomic orbitals. H(1s)–I(5p) Similarly if we consider the elemental form of the halogens F 2 We can describe the bonding more specifically in the following way H(1s)–F(2p) Movie When the 1s orbital on hydrogen overlaps with the np orbital on the halogen the covalent bond is formed. When we look at the orbital diagram for hydrogen and the halogen we see the 1s orbital on hydrogen contains one unpaired electron, and an np orbital on the halogen also contains one unpaired electron. The covalent bond that is formed between the hydrogen atom and the halogen is formed from the overlap of the 1s orbital on hydrogen and the np orbital on the halogen. HI The electron configuration for the halogen is ns 2np 5 and the electron configuration for H is 1s 1. Valence Bond Theory and Hybrid Orbitals Valence Bond Theory In the simplest terms covalent bonds are formed when atomic orbitals on two nonmetal atoms overlap to share electrons.
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