Native Used to describe a metal that is found as an element even though it may be mixed with other substances. Gold is often (!) found native. Even though it may not be in large lumps, it is not chemically combined with another element.
Natural gas The fossil fuel that is formed (usually along with crude oil) when the remains of dead sea creatures decompose over millions of years. It is composed mainly of methane (CH4) and it is the gas that is used in the home and in school for Bunsen burners.
Neutral A substance that is neither acidic nor alkaline. It has a pH of 7.
Neutralisation A reaction where an acid "cancels out" an alkali.
Neutral oxide Although most metal oxides are bases and most non-metal oxides are acidic, a few form netral solutions in water. One example of this kind of oxide is carbon monoxide.
Nirogen oxides When nitrogen enters the cylinders of a car engine, it can be burned to fform a variety of oxides. Rather than deal with all the different ones individually, it is useful to discuss them together as "nitrogen oxides". They are sometimes written as NOx. They are removed fromthe exhaust gases of a car by using a catalytic converter.
Non-metals Although this sounds like it ought to be everything that is not a metal, it really means the elements that are not metals. The non-metals are usually dull, have low melting and boiling points and do not conduct electricity There are some exceptions though like the graphite form of carbon which can conduct electricity.
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