Why is aluminum a substance

Aluminum is a substance because it is a particular type of matter that has particular and unique properties. Aluminum is a unique element with a place on the periodic table. 

Aluminum is a substance because it is a particular type of matter that has specific and unique properties, It is element number 13 on the periodic table making it a  "pure substance." It is impossible to separate Aluminium in two or more components; neither can Aluminium present different properties at different times; therefore it can be classified as a substance. Aluminum cannot be decomposed (separated by chemical methods) in two or more elemental substances or elements, which makes it an element as well.  

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