A pure substance has a constant composition and cannot be separated into simpler substances by physical means. There are two types of pure substances: elements and compounds. Elements: are pure substances made up of only l type of atom. Atoms of the same element are identical in properties.
There are more than 109 different types of atom - one for each element. Differences between the atoms give the elements their different chemical properties. In 2001, there were 115 known elements. However, those above 109 are highly unstable and have been made in only tiny quantities
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Answer:
A pure substance has a constant composition and cannot be separated into simpler substances by physical means. There are two types of pure substances: elements and compounds. Elements: are pure substances made up of only l type of atom. Atoms of the same element are identical in properties.
Answer:
109 different types
Explanation:
There are more than 109 different types of atom - one for each element. Differences between the atoms give the elements their different chemical properties. In 2001, there were 115 known elements. However, those above 109 are highly unstable and have been made in only tiny quantities