Why does dew form on a cool morning

Many people love cool autumn mornings, with the scent of the cool air and a rich dew underfoot on the grass and paths. The dew forms when molecules of water from the air coalesce, because of the cool temperature, to form minute aggregates that subsequently nucleate to form visible drops of water. These water drops form a stable colloid (see Chapter 10). 

These excess charges form in consequence of the molecule incorporating a variety of atoms. For example, the magnitude of 5 on the chlorine of H-Cl is larger than the excess charges in the F-Cl molecule, because the difference in electronegativity 

The symbol S means a small amount of. .., so S is a small amount of negative charge. 

X between H and Cl is greater than the difference between F and Cl. There will be no excess charge in the two molecules H-H or Cl-Cl because the atoms in both are the same - we say they are homonuclear. Table 2.1 contains a few electronegativities. 

2 By looking at the electronegativities in Table 2.1, suggest whether the bonds in the following molecules will be polar or non-polar (a) hydrogen bromide, HBr (b) silicon carbide, SiC (c) sulphurdioxide, 0=S=0 and (d) sodium iodide, Nal. 

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