解析 A。“Atom”在科学中意为“原子”,是构成物质的非常小的粒子;B 选项“a large object in space”指“太空中的大物体”;C 选项“a form of energy”是“一种能量形式”;D 选项“a type of wave”是“一种波”。因此选 A。 反馈 收藏
Atoms have great variations in weight, although they are all about the same size. The diameter of an atom is a million times smaller than one strand of thick human hair, very tiny indeed. The diameters of atoms range from approximately 0.1 to 0.5 nanometers. For example, plutonium, which ...
By small, I really do mean absolutely, nanoscopically tiny: a single atom is hundreds of thousands of times thinner than a human hair, so you have absolutely no chance of ever seeing one unless you have an incredibly powerful electron microscope. In ancient times, people thought atoms were ...
This latter is a naturally abundant organic coordination molecule with the chemical structure of C6H18O24P6 in which each phosphate group, characterizing the molecule, is connected to a carbon atom of the cyclo-hexamehexol ring [95]. Thanks to its non-toxicity, biocompatibility and environmental...
A U.S. lab has successfully sparked a fusion reaction that released more energy than went into it. But there’s still a long way to go toward fusion as a clean energy source.
but it is not exactly science. In the same sense, if you were discussing what art is, you wouldn’t say art is the knowledge of the fact that a 3-B pencil is softer than a 2-H pencil. It’s a distinct difference. That doesn’t mean an art teacher shouldn’t teach that, or th...
However, when we talk about the density of matter in the universe, we're imagining spreading every atom in the universe (three-quarters of which are hydrogen) evenly across space. There's also dark matter, which we can infer only from its gravitational effects, but we know it must account...
(e.g., Watson and Crick’s metal model of DNA, or the fruit fly and other model organisms in biology), but most of them are abstract/mathematical objects (e.g., Bohr’s model of the atom, the Lotka-Volterra model of predator-prey interaction, the Newtonian model of the solar system...
What does 'elements made up of atoms with the same number of protons' mean? What is associative law? What is the difference between oxidation state and valency? What's the importance of atom economy? Why are polyatomic ions not neutral? Do all atoms achieve octet when they bond? What is...
Whereas, in science, an element is a substance entirely made of one type of atom. 10 The essence of a concept or thing often remains abstract and philosophical, focusing on underlying qualities. Elements are more concrete, representing tangible or specific parts that can be isolated and defined...