There are also other properties which distinguish different liquids, which are a function of the size and shape of the molecules and how the electrons distribute themselves over the molecule leading to the molecules having positively and negatively charged regions.

These factors affect properties such as density, viscosity (is it like water or thick syrup), how it mixes with other liquids, what groups of other substances dissolve in it, and also a property which affects how it 'wets' a solid surface. This last corresponds closest to what we might informally think of as 'wetness', in that it determines whether the liquid tends to soak into a piece of cloth or not, for example. It determines whether it tends o spread out into a film covering the surface at one extreme, or remain as individual droplets.

I guess the point is that all of these properties of a given chemical compound, including whether it is even a liquid in a given range of temperature, are normally very different from those of the individual elements of which it is composed.

One of the key factors affecting 'wetting' of a surface by a liquid is the degree of polarity of the molecules, which is a measure of the degree to which different parts of the molecule display an effective electrical charge, and water is quite strongly polarised, which means that the molecules tend to attract each other, and other polarised molecules, fairly strongly. Whereas liquids hydrogen and oxygen do not show this property.

It is not a perfect analogy for emergent properties, I will concede, so you do have some point there.

It occurs to me that a better argument might be based on pointing to the huge range of properties exhibited within particular classes of substances which all have the same constituent elements, such as 'hydrocarbons' which include gasses, like methane, liquids (at normal temperatures) like octane and related substances making up the major components of gasoline, to polythene plastics. All of these are composed of the same two elemenst, hydrogen and carbon.

Perhaps, but in my materials science courses I learned that wetness is the ability of a substance to wet a surface. It a liquid will spread across a surface then that is wetness. But perhaps others use different definitions then my professors. We look at wetness in terms of surface energy. If someone wants I can go into this in more depth, but it is a rather dull subject. And for all I know my understanding of wetness is from a peculiar materials science point of view.

  Intersting little tid-bit of knowledge.  See, participating in an atheist forum isn't always about arguing over theism. Thanks MMF.

Liquid nitrogen blue?  I'd question the source of the nitrogen being chilled as it's undoubtedly contaminated with oxygen.  Liquid nitrogen is colourless.

M