You call it an isotope. And it isn't always heavier; it can be lighter, too. An isotope is an atom of a certain element with a different number of neutrons. It usually has a lot of the same physical and chemical properties of the parent element, but it will have a different Atomic Mass because of the different neutron count. Many isotopes are radioactive, and therefore unstable, since they undergo decay over a certain period of time. Isotopes make possible radiocarbon dating and smoke detectors, so they're quite useful.
ion
It's still an atom. It would be a different isotope of the same element.
Isotopes of elements have different atomic mass'.
Atomic number and it also tells the number of protons and electrons in an atom it is on top of the element symbol.
The number of protons in the nucleus of an atom will determine its chemical identity. Only that. The number of neutrons can vary a bit, depending on the element, and we call these variations isotopes of that element. Electron count will match proton count only in a neutral atom. Rememeber that atoms loan out and borrow electrons, which is what chemistry is all about.
ion
An element.
You call a substance with only one type of atom, an element.
An atom of a different element.
element
It's still an atom. It would be a different isotope of the same element.
an isotope
isotopes
By definition, an Element contains only one kind of atom - atoms of that element. If it has more than one kind, it is a compound, not an element.
An element.
The element Hydrogen
A substance that is made up of only one atom is called a pure substance. A pure substance is also called an element on the Periodic Table.