Atoms, Elements, Molecules, & Compounds Flashcards
atom
the smallest particle of an element that can exist
element
a pure chemical substance that cannot be physically split into a more simple substance. each one is made of one type of atom. carbon, mercury, and hydrogen are examples
molecule
the smallest particle of a substance that can exist. it is composed of two or more atoms
compound
a substance made of atoms from two or more elements
proton
a particle of matter that has a positive electrical charge and found in the nucleus of an atom
neutron
a particle of matter that has no electrical charge and found in the nucleus of an atom
electron
a particle of matter that has a negative electrical charge and travels around the nucleus of an atom
atomic number
= the number of protons in an element’s atoms. top number in the element box
mass number
number of protons plus neutrons. bottom number in the element box
chemical symbol
a one or two letter representation of an element
subscript
tiny number to the right of the element symbol. tells you how many atoms of that element