|What is a chemical??|
|Everything is a chemical. Longer answer: Chemistry is the study of matter and its interactions with other matter. Anything made of matter is therefore a chemical. Any liquid, solid, gas. Any pure substance; any mixture. Water is a chemical. Technically speaking, so is a chunk of your computer. A chemical can often be broken down into components, as is true with your computer. However, people generally use the term 'chemical' to refer to a substance that appears homogeneous or the same throughout its structure.|
|Turning Lead into Gold???|
Before Chemistry was a science, there was
Alchemy. One of the supreme quests of alchemy is to
transmute lead into gold. Lead (atomic number 82) and gold (atomic
number 79) are defined as elements by the number of protons they possess.
Changing the element requires changing the atomic (proton) number. The
number of protons cannot be altered by any chemical means. However, physics
may be used to add or remove protons and thereby change one element into
another. Because lead is stable, forcing it to release three protons
requires a vast input of energy, such that the cost of transmuting it
greatly surpasses the value of the resulting gold.
Transmutation of lead into gold isn't just theoretically possible - it has been achieved! There are reports that Glenn Seaborg, 1951 Nobel Laureate in Chemistry, succeeded in transmuting a minute quantity of lead (possibly en route from bismuth, in 1980) into gold.
There is an earlier report (1972) in which Soviet physicists at a nuclear research facility near Lake Baikal in Siberia accidentally discovered a reaction for turning lead into gold when they found the lead shielding of an experimental reactor had changed to gold.
Today particle accelerators routinely transmute elements. A charged particle is accelerated using electrical and/or magnetic fields. In a linear accelerator, the charged particles drift through a series of charged tubes separated by gaps. Every time the particle emerges between gaps, it is accelerated by the potential difference between adjacent segments. In a circular accelerator, magnetic fields accelerate particles moving in circular paths. In either case, the accelerated particle impacts a target material, potentially knocking free protons or neutrons and making a new element or isotope. Nuclear reactors also may used for creating elements, although the conditions are less controlled.
In nature, new elements are created by adding protons and neutrons to hydrogen atoms within the nuclear reactor of a star, producing increasingly heavier elements, up to iron (atomic number 26). This process is called nucleosynthesis. Elements heavier than iron are formed in the stellar explosion of a supernova. In a supernova gold may be made into lead, but not the other way around.
While it may never be commonplace to transmute lead into gold, it is practical to obtain gold from lead ores. The minerals galena (lead sulfide, PbS), cerussite (lead carbonate, PbCO3), and anglesite (lead sulfate, PbSO4) often contain zinc, gold, silver, and other metals. Once the ore has been pulverized, chemical techniques are sufficient to separate the gold from the lead. The result is almost alchemy...almost.
Which one is the most abundant element????
The most abundant element in the universe is hydrogen, which makes up about 3/4 of all matter! Helium makes up most of the remaining 25%. Oxygen is the third most abundant element in the universe. All of the other elements are relatively rare.
The chemical composition of the earth is quite a bit different from that of the universe. The most abundant element in the earth's crust is oxygen, making up 46.6% of the earth's mass. Silicon is the second most abundant element (27.7%), followed by aluminum (8.1%), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%). and magnesium (2.1%). These eight elements account for approximately 98.5% of the total mass of the earth's crust. Of course, the earth's crust is only the outer portion of the earth. Future research will tell us about the composition of the mantle and core.