The subscript “2” behind hydrogen means there are 2 atoms of hydrogen; if there is only one atom, the subscript 1 is omitted
Molecular formulas do not tell any information about the structure (the arrangement of the various atoms).
- Page 215 These are some of the different ways to represent ammonia: 1. The molecular formula shows how many atoms of each element are present 2. The structural formula ALSO shows the arrangement of these atoms! 3. The ball and stick model is the BEST , because it shows a 3-dimensional arrangement.
It is a hybrid of both, like a mule; and shown by a double-headed arrow
found in double-bond structures!
Resonance in Ozone Neither structure is correct, it is actually a hybrid of the two. To show it, draw all varieties possible, and join them with a double-headed arrow. Note the different location of the double bond
Network solids melt at very high temperatures, or not at all (decomposes)
Diamond does not really melt, but vaporizes to a gas at 3500 o C and beyond
SiC, used in grinding, has a melting point of about 2700 o C
Covalent Network Compounds Some covalently bonded substances DO NOT form discrete molecules. Diamond, a network of covalently bonded carbon atoms Graphite, a network of covalently bonded carbon atoms