have distinctly visible partsLook at a Periodic Most materials we encounter in theTable. There are 113 world are mixtures. The air weelements in the breathe is a mixture of oxygen,Periodic Table nitrogen, and other gases. The oceans are mixtures of water, salts and other substances
A pure substance has a definite and constant composition — like salt or sugar. The composition of a pure substance doesn’t vary.An element is composed ofa single kind of atom. A compound is composed of two or moreChemists CAN’T separate elements in a specific ratio. For example, water is a compound made upthe components of a of two elements, hydrogen (H) and oxygencompound AT ALL. (O). Chemists can’t easily separate the components of a compound: They have to resort to some type of chemical reaction.
the different parts of a mixture can be easily separated by physical means, such as filtration. For example, suppose you have a mixture of salt and sand, and you want to purify the sand by removing the salt. You can do this by adding water, dissolvingMixtures are physical the salt, and then filtering thecombinations of pure substances mixture. You thenthat have no definite or end up with pureconstant composition — the sand.composition of a mixture variesaccording to who prepares themixture.