atomic number protons + neutrons = atomic mass
TRANSCRIPT
ISOTOPES
FROM THE PERIODIC TABLE – WHAT NUMBER EQUALS THE NUMBER OF PROTONS?
Atomic Number
FROM THE PERIODIC TABLE – HOW IS THE MASS OF A “REGULAR” (MOST ABUNDANT) ATOM DETERMINED?
Protons + Neutrons = Atomic Mass
AN ISOTOPE IS DEFINED AS… An Atom of an Element that has the
same number of protons as another atom of the same element but a different number of neutrons.
THE ELEMENT HYDROGEN, FOR EXAMPLE, HAS THREE COMMONLY KNOWN ISOTOPES: PROTIUM, DEUTERIUM AND TRITIUM.
SINCE THE ATOM HAS THE SAME PROTONSIsotopes of an element have the same
chemical properties.
LITHIUM
ONE WAY TO WRITE THE ISOTOPE
ANOTHER WAY TO WRITE THE ISOTOPE
Na - 23
WHY ARE THE MASSES ON THE PERIODIC TABLE DECIMAL NUMBERS?
Average of all the isotopes of that element
IF AN ATOM HAS A DIFFERENT NUMBER OF NEUTRONS May make the element have a different
radioactivity.
Radioactivity is the release of energy and matter that results from changes in the nucleus of an atom
An isotope that is radioactive is called a radioisotope or radionuclide. The
RADIOACTIVE ISOTOPESOften called Radioisotopes
How does this happen?An additional neutron or two may upset
the nucleus and cause the atom to become unstable. In an unstable atom, the nucleus changes by giving off a neutron to get back to a balanced state. As the unstable nucleus changes, it gives off radiation and is said to be radioactive.
ELEMENTS WITH ATOMIC # GREATER THAN 83 Are Radioisotopes Have unstable nuclei and are
radioactive.
ELEMENTS WITH ATOMIC # GREATER THAN 83 AND LESSHave isotopes with a stable nucleus
And
Most have at least one radioisotope with an unstable nucleus.