atoms elements molecules and 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 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
compounds
a substance made of atoms from two or more different elements
proton
a particle of matter that has a positive electrical charge and found in 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 no 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 box
mass number
number of protons plus neutrons bottom number in the box
chemical symbol
a one or two letter representation of an element
subscript
tiny number to the top right of the elements symbol tells how many atoms of that element