arbon, as with many elements, can arrange its atoms into several different geometries, or "allotropes." In pure diamond, every carbon atom is covalently bonded to exactly 4 other carbon atoms in a very specific and energetically favorable geometry. The diamond cannot be broken or scratched unless many covalent bonds are broken, which is difficult to do. In another common allotrope, graphite, every carbon atom is covalently bonded to only 3 other carbon atoms, and the atoms are arranged in sheets that are not covalently bonded to each other. The sheets can be broken apart easily, ultimately meaning that graphite can be easily scratched. Coal is composed of particles of different allotropes of carbon, and some "amorphous carbon," which has no defined geometry in its atomic structure. Without a continuous network of covalent bonds, coal is easily scratched (i.e. it is not hard).
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threaten the food webs of their invaded habitat and effect the ecosystem.
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Food must be broken down into nutrients for the body to use for energy, development, and cell repair. Before the blood absorbs and transports nutrients to cells in the body, food and drink must be broken down into smaller nutrient molecules.
Internal fertilization is the process when the syngamy (union of male and female gamete) occurs inside the female body after insemination using copulation. In contrast, External fertilization is the syngamy outside the female body, that is in the outer environment especially in water bodies.
