3g. The covalent bonding in the water and hydrogen sulfide molecules
Doc Brown's Chemistry: Chemical Bonding and structure GCSE level, IGCSE, O, IB, AS, A level US grade 9-12 level Revision Notes
Covalent bonding diagram for WATER covalent molecule, molecular formula H2O
Two atoms of hydrogen (1) combine with one atom of oxygen (2.6) to form the molecule of the compound water H2O
* metals \ non-metals (zig-zag line)
Hydrogen is one electron short of a full shell, oxygen is two electrons short of a full outer shell of 8, so two hydrogen atoms share their electrons with the six outer electrons of oxygen, so all three atoms now have a full outer shell.
and and combine to form so that the hydrogen atoms are electronically like helium and the oxygen atom becomes like neon (2.8, but only the outer shell of oxygen's electrons are shown).
Electronically, hydrogen (1) becomes like helium (2) and oxygen (2.6) becomes like neon (2.8), so the hydrogen and oxygen atoms effectively have full outer shells in forming the covalent bonds when the atoms share their outer electrons.
(Lewis diagram of water) simplified 'dot and cross' electronic diagram for the covalently bonded water molecule.
The water molecule is held together by the strong H–O hydrogen–oxygen single covalent bonds by sharing electrons.
The molecule can be shown as (displayed formula of water) with two hydrogen – oxygen single covalent bonds.
The 'pros and cons' of molecular diagrams and understand the limitations of diagrams:
On the above right is the ball and stick diagram for the water molecule.
The diagrams on the left and right are the full 'dot and cross' electronic diagram for the covalent bonding in the water molecule. All the electrons are shown in this electronic dot & cross Lewis diagrams for covalent bonding in the water molecule.
The dot and cross diagram does not tell you anything about the size of the atoms in the molecule or the accurate 3D spatial arrangement of the atoms, that is, the shape of the molecule
Hydrogen sulphide will be similar, since sulphur (electrons 2.8.6) is in the same Group 6 as oxygen.
Valency of oxygen is 2 and sulphur is also 2 here.
The dot and cross Lewis diagram for hydrogen sulfide is similar to water.
Sulfur is in group 6 with six outer shell electrons, two of which pair up with the electrons from the two hydrogen atoms.
It has a bent shape like water.
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