exchemist

Do you understand the principle of resonance structures, e.g. in benzene? Here is how it works: Now try to apply something similar to the structure you have been given. Can you do that?

That's interesting and I fully admit I am pretty rusty on a lot of this stuff. I had in mind as typical H bond strengths of the order of 5-10kcal/mol (showing my age). Can you give examples of much stronger ones?

I'm not a mineralogist, but I can try to add a bit to what others have said, based on what I have quickly been able to read up.😉 Clays are made up of tiny crystals of "clay minerals" and water. The water is hydrogen-bonded to the surface of the crystals, which means it is attached by bonds that are about a tenth the strength of a full "normal" chemical bond. A crystal of dry clay mineral will tend to absorb water until there is a hydrogen bonded film of water all along its surface. Clay minerals are made of sandwiches of sheets of silicate tetrahedra, which have a -ve charge, with metal ions in between that have a +ve charge, thus making the whole sandwich electrically neutral, and then water molecules in between one sandwich and the next. (Though some are Danish open sandwiches with only one layer of silicate "bread" under the metal ions and nothing on the top.) Because they have a sheet structure, these minerals easily cleave along the lines of the sheets, as mica does. What you end up with is a lot of microscopic, flat, very thin flakes of clay mineral, with water in between. It is the water that makes clay plastic, enabling you to mould it, as it allows the flat flakes to slide past one another. In terms of chemical bonding, you have covalent bonding within and between the silicate tetrahedra, ionic bonding between the sheets of tetrahedra and the metal ions in the sandwich, and finally hydrogen bonding of water molecules along the outside of the sheets. So clays are chemically quite complicated things, dull though they may look from the outside. So when you ask if clay is uniform or homogenous, it depends on at what level you mean. Macroscopically it is, but at the molecular level it is made of two distinct phases, a solid mineral and liquid water - albeit much of the water is hydrogen bonded to the mineral so that it does not behave entirely like a liquid. Moulding the clay does nothing to this structure. However, drying or firing the clay will drive off most of the water, shrinking the clay and hardening it by allowing the layers to link together directly instead of being kept apart by a layer of water. Here's a diagram I found which may help visualise it:

Addressing your point about credibility of a smoothy containing CaCO3, this is certainly possible if it is dispersed in colloidal form. In my former work in the lubricants industry, we used to put "overbased" detergents in engine oils. These contained sometimes quite high amounts of colloidal CaCO3, which was useful to neutralise the acids formed by the combustion of the fuel, thereby avoiding corrosion of the cylinder liners in the engine. The CaCO3 was bound inside "micelles" of detergent molecules, forming a sort of cage around each sub-micron particle of what was effectively chalk, allowing it to remain suspended in the oil almost indefinitely. I believe the same idea is used in medicines such as "milk of magnesia", which is used for heartburn - though the suspended material in that case is Mg(OH)2 rather than CaCO3. However I have no idea what substance is used to stabilise the suspension in these cases.

Scattering. Visible light tends to be scattered by tiny droplets in the air, whereas radio waves are not because their wavelength is far longer than the dimensions of the droplets. But I can't immediately see why simple humidity, i.e. without any condensed droplets, would weaken a LIDAR signal.

Nice flamebait attempt. 😁 Speaking as one who is not a "religion fanatic", but was brought up Christian, my understanding is it is so called because Christians believe the sacrifice of Christ on the cross atoned for the collective sins of mankind and made a new contract with God. The word "good" is used in its now obsolete sense of holy.

This is rather unclear. Can you rephrase?

I don't think the intervals of the octave are arbitrary, actually. If you take a fundamental and consider its harmonics (say a vibrating string with one, two, three, four etc standing waves), you start to get the other intervals that make up the musical scale. For example a C fundamental will have a 1st harmonic of C at the octave above, but the 3rd harmonic will be G at the octave plus a fifth above, the 4th will again be C but 2 octaves up, and the 5th harmonic will be E, a major third up from that (I think: it is hard to remember exactly how it works). So it is not coincidence that the major triad in harmony has the tonic, fifth and major third in it. These pitches are all part of the same family of overtones, from an implied lower fundamental. From what I recall, most of the notes of the Pythagorean scale were derived in this sort of way. The pentatonic scale, I think, still has the intervals of the third and the fifth in it, so is not inconsistent with the same physical principles - unsurprisingly.

Surely the point about octaves is that if you double the frequency you get something that resonates with the fundamental. And if you double it again, the same occurs. So doubling has a real significance, both from the point of view of physics and from the point of view of the hearer. In fact, when you play a certain pitch on any instrument, you also excite a whole series of so-called "overtones" at the same time, which are frequency multiples of 2, 4, 8 etc above the fundamental. You also get a sort of resonance at the fifth of the scale. It sounds, well, harmonious. Whereas if you play 2 pitches that are only a tone, or semitone, apart, you get no resonance but a harsh sounding beat frequency as the two pitches go in and out of phase with one another. So I do not think it is just a matter of convention. Doubling the frequency has a physical significance that the ear recognises.

Animal Farm and 1984 are rightly considered classics. They are so powerful that they may have helped prevent the spread of authoritarian political systems. Possibly the only remaining 1984 society now is N Korea. But I also very much like "Coming Up for Air." There is lesson there in the mixed success one has in attempting to revisit one's past, which I find poignant.