Structure of the Atom: Subatomic Particles Nucleus= small dense central portion of the atom that is made up of protons and neutrons • Proton = positive • Location: Nucleus • Neutron = neutral • Location: Nucleus • Electron = negative • Location: Outside the nucleus (electron cloud)
Atomic Number = # of protons • Each element has a different atomic number —gives the atom its identity • Also indicates the number of electrons in a neutral atom of the element
Mass Number = # protons + # neutrons • Can be different for different atoms of the same element • Cannot help in identifying an element… • different elements can have the same mass number and… • a single element can have different mass numbers
Isotopes • Atoms of the same element that have different numbers of neutrons
Neutron Nucleus Proton Proton + Nucleus + Neutron + + + Carbon-12 + + + + + + + Carbon-14 Isotopes Electrons Nucleus Electrons Neutrons 6 Protons 6 Electrons 6 Neutrons 8 Protons 6 Electrons 6 Nucleus
Please practice your knowledge of atomic number and atomic mass, by working on chart on top of page 2.