ISOTOPES AND

NUCLEAR REACTIONS

ISLAND OF STABILITY

ISOTOPES

• A VARIATION OF AN ELEMENT, THAT DIFFERS BY THE NUMBER OF NEUTRONS.

• PROTONS CANNOT CHANGE – A PROTON IS LIKE AN ATOMS DNA, ITS WHAT MAKES IT AN ATOM OF A SPECIFIC ELEMENT

• ELECTRONS ARE SO SMALL – THEIR MASS IS NEGLIGIBLE TO THE MASS OF AN ATOM

• NEUTRONS ARE THE ONLY THING THAT CAN CHANGE – CHANGE THE MASS OF THE ATOM

• WHEN AN ATOM VARIES IN THE NUMBER OF NEUTRONS, ITS MASS ALSO VARIES – THESE ARE CALLED ISOTOPES

ISOTOPIC NOTATION

• HOW DO WE DIFFERENTIATE BETWEEN DIFFERENT ISOTOPES?

• ISOTOPES CAN BE WRITTEN IN A LONG FORMAT THAT USES THE ELEMENTS NAME AND MASS

• CARBON – 12

• CARBON – 13

• CARBON - 14

• ISOTOPES CAN BE WRITTEN WITH SYMBOLS JUST LIKE ELEMENTS CAN:

PRACTICE WITH ISOTOPIC NOTATION

Element Isotopic Symbol

Mass Number

Atomic Number

Number of Protons

Number of Electrons

Number of Neutrons

Carbon – 14 14 6 6 6 14-6= 8

Polonium – 210

210 84 84 84 210-84= 126

Aluminum - 27

27 13 13 13 27-13= 14

ATOMIC MASS

• RECALL WHAT ATOMIC MASS IS:

• AVERAGE ATOMIC MASS IS THE MASS OF ALL THE ISOTOPES OF AN ELEMENT COMBINED

• IT IS THE MASS GIVEN ON THE PERIODIC TABLE

• IT IS CALCULATED BY TAKING THE MASS OF EACH ISOTOPE OF AN ELEMENT AND MULTIPLYING EACH ISOTOPES MASS BY ITS ABUNDANCE THEN ADDING ALL THE ISOTOPES TOGETHER.

• (% OF MASS 1)(MASS 1) + (% OF MASS 2)(MASS 2) + (% OF MASS 3)(MASS 3)….. • YOU WOULD DO THIS FOR EACH ISOTOPE OF THE ELEMENT – SOME ELEMENTS HAVE MANY

ISOTOPES

• POLONIUM HAS 25 ISOTOPES AND ALL ARE RADIOACTIVE

AVERAGE ATOMIC MASS PROBLEMS:

• COPPER HAS TWO ISOTOPES: 69.2% OF ALL COPPER HAS A MASS OF 63 AMU, WHILE 30.8% OF ALL COPPER HAS A MASS OF 65 AMU. WHAT IS COPPER’S AVERAGE ATOMIC MASS?

NUCLEAR CHEMISTRY

• RADIOACTIVITY – THE PROCESSES BY WHICH UNSTABLE NUCLEI ACHIEVE STABILITY BY RELEASING RADIATION

• RADIATION – THE PENETRATING RAYS AND PARTICLES EMITTED BY A RADIOACTIVE SOURCE

• RADIOACTIVE DECAY – THE PROCESS IN WHICH UNSTABLE NUCLEI DISINTEGRATES

• RADIOISOTOPES – AN ISOTOPE THAT HAS AN UNSTABLE NUCLEUS AND UNDERGOES RADIOACTIVE DECAY

NUCLEAR REACTIONS

•A REACTION THAT RESULTS IN A DIFFERENT NUCLEUS

• ALL REACTIONS KNOWN UP TO THIS POINT, HAVE NOT CHANGED THE NUCLEUS

• LAW OF CONSERVATION OF MASS

• NUCLEAR REACTIONS DO NOT SEEM TO FOLLOW THIS LAW.

FISSION AND FUSION REACTIONS

FISSION

• NUCLEAR DECAY THAT RESULTS FROM THE NUCLEUS OF AN ATOM SPLITTING IN TO SMALLER PIECES

• HEAVIER ATOM BECOMES A LIGHTER ATOM

• THE IS NUCLEAR ENERGY ON EARTH

• REQUIRES LITTLE TO NO ENERGY (USUALLY)

• RESULTS IN: FREE FLOATING NEUTRONS AND PHOTONS (ENERGY)

FUSION

• NUCLEAR REACTION THAT RESULTS FROM TWO NUCLEI JOINING TOGETHER TO FORM ONE LARGER NUCLEUS

• DOES NOT OCCUR ON EARTH

• IF IT DID, IT WOULD SOLVE OUR ENERGY CRISIS

• RELEASES GAMMA RADIATION FOR EVERY REACTION

• THIS IS WHAT WE COULD USE FOR ENERGY

• REQUIRES TOO MUCH ENERGY TO START THE REACTION

• POWERS ACTIVE STARS

FISSION AND FUSION

• FISSION VS FUSION

RADIATION

•RAYS AND PARTICLES EMITTED BY THE RADIOACTIVE MATERIAL

• 3 TYPES• ALPHA

• BETA

• GAMMA

ALPHA RADIATION

• ALPHA PARTICLES ARE MADE OF 2 PROTONS AND 2 NEUTRONS

• HAS A +2 CHARGE

• THE ATOMIC MASS DECREASES BY 4 AND THE ATOMIC # BY 2

• IT IS A VERY WEAK TYPE OF RADIATION

• CAN BE STOPPED BY PAPER OR CLOTHING

• LIMITED TO VERY LARGE NUCLEI

• EX: HEAVY METALS

BETA RADIATION• CHANGES A NEUTRON TO A PROTON, EMITS FAST MOVING ELECTRONS FROM

THE NUCLEUS

• -1 CHARGE

• DOES NOT AFFECT MASS BUT INCREASES THE ATOMIC NUMBER BY 1

• CAN BE STOPPED BY: ALUMINUM FOIL, THIN PIECES OF WOOD

GAMMA RADIATION

• HIGH ENERGY RADIATION WAVE OF ELECTROMAGNETIC RADIATION GIVEN OFF BY A RADIOISOTOPE

• NOT A PARTICLE, BUT A WAVE OF ENERGY

• NO CHARGE

• RELEASED WITH ALPHA AND BETA RADIATION

• DOES NOT CHANGE THE MASS OR ATOMIC NUMBER

• VERY HARD TO STOP

• CAN ONLY BE STOPPED BY THICK CONCRETE OR LEAD

HOMEWORK

• PAGE 7 AND 8 IN YOUR PACKETS

• WE WILL COMPLETE PAGE 9 TOGETHER ON THURSDAY – YOU MAY TRY IT IF YOU WANT