complex carbohydrate that makes up the cell walls of fungi, also found in the external skeletons of arthropods

Answer:

chitin

anything takes up space and has mass

Answer:

matter

substance consisting of two or more elements in a fixed ratio

Answer:

compound

any substance that cannot be broken down to any other substance

Answer:

element

an element indispensable for life but required in extremely minimum amounts

Answer:

trace elements

smallest unit of matter that retains property of an element

Answer:

atom

an electrically neutral particle found in the nucleus of an atom

Answer:

neutron

a subatomic particle with single positive charge found in nucleus of an atom

Answer:

proton

a subatomic particle with a single negative charge; one or more electrons move around the nucleus

Answer:

electron

one of several atomic forms of an element each containing different number of neutrons and different in atomic mass

Answer:

isotopes