Flashcards in chapter 4 Deck (61):
What makes a stable nuclei
the force of attraction and repulsion are balanced
which elements usually have a stable nuclei, and which don't
element below atomic number #19 usually have a stable nuclei, elements atomic number #20 and above usually don't have stable nuclei
what makes a nuclei unstable?
too many or too few protons compared to number of neutrons therefore the forces are unbalanced
energy emitted by unstable nuclei to become more stable
isotopes that emits radiation
change in number of protons in nucleus (atom of an element converted to a different element)
Which elements are produced artificially?
elements #93 or higher on the periodic table are produced in nuclear labs
How does emitting radiation help atoms be more stable?
an unstable nucleus forms a more stable, lower energy nucleus
What are the types of radiation?
alpha particles, beta particles, positron, Gamma rays
identical to helium nucleus (2 protons, 2 neutrons, mass number 4, atomic number 2, charge of 2+
high energy electron with a charge of 1-, mass number 0
when do beta particles form?
when a neutron in an unstable nucleus changes to a proton and an electron.
positive 1+ charge with a mass of 0, it is an antimatter
when is a positron produced?
it is produced by the unstable nucleus when a proton is transformed into a neutron and a positron
How are gamma rays produced?
when a positron and an electron collides
when radiation hits molecules in its way, electrons may be knocked away forming unstable ions
why is ionization energy harmful for humans
if it passes through human body, it might interact with water molecules removing electrons and producing H20+
Which type of cells are most sensitive to ionization radiation? and examples?
cells that undergo rapid cell division, such as bone marrow, skin, reproductive organs, cells of growing children and cancer cells
materials used to provide protection from radioactive sources
Alpha particles protection?
paper, skin, clothing
how do alpha particles travel?
in the air for a few cm before they collide with air molecules , acquire electrons and become helium
Beta particle shielding
heavy clothes such as lab coats and gloves
which radiation particle has the largest mass?
Gamma rays protection
only dense shielding such as concrete and lead.
how far can gamma rays travel?
How does one protect self from radiation?
greater distance from radioactive source and less exposure/time with radioactive source
What happens during radioactive decay?
unstable nucleus breaks down and releases high energy radiation
equation of a nuclear reaction:
Radioactive nucleus-->new nucleus + radiation
What happens to a radioactive nucleus during an alpha decay reaction?
The mass of the nucleus goes down by 4 and atomic number (protons) goes down by 2.
What happens to a radioactive nucleus during a beta decay?
the mass stays the same, the atomic number (protons) increases by 1.
What happens to a radioactive nucleus during a positron emission
mass number stays the same, the atomic number (protons) goes down by 1
What happens to a radioactive nucleus during a gamma emission?
the mass number and atomic number stays the same.
Most common source of alpha particle
most common source of beta particle
most common source of gamma particle
why are pure gamma emissions rare?
they accompany most alpha and beta radiation
converting stable nonradioactive isotopes into radioactive ones
What is different about all atomic numbers 92 and above? and how?
they are created in labs through transmutation by bombarding high speed particles (protons, neutrons and small nuclei) and when absorbed by stable nucleus, radioactive isotopes are created.
How and why is Technetium-99m used in nuclear medicine?
for diagnostic purposes (brain tumors, spleen and liver examinations) since they pass through the body
instrument for measuring radiation (beta and gamma)
what unit measures disintegration per second of radiation?
becquerel (Bq) (SI UNIT)
3.7 x 10^10 disintergrations per second
1 disintegration per second
what is disintegration?
activity of sample (radiation)
what unit measures amount of radiation absorbed by a g of a material?
rad (radiation absorbed dose)
Gray (Gy) (SI UNIT)
1 Gy= ___rad
1 Gy= 100 rad
what unit measures the biological effects of different kinds of radiation?
rem (radiation equivalent in humans)
sievert (sv) (SI UNIT)
formula to calculate rem?
biological damage (rem)= absorbed dose (rad) x factor (of radiation)
what is the factor of:
Gamma, beta: 1
high energy proton, neutron: 10
1 sv= __rem
1 rem=__ mrem
1 sv= 100rem
1 rem= 1000 mrem
how much radiation does an average person in the US get annually?
360 mrem /year
How does a geiger counter measure radiation?
uses ions produced by radiation to create an electrical current
why is radiation used in medicine?
they have short half lives
how much radiation is considered undetected on body?
lethal dose of radiation
Large nucleus split into smaller pieces releasing energy
Process of fission
Releases neutrons and large amounts of gamma radiation and energy
1. Neutron collides with nucleus (of uranium)
2. Nucleus becomes unstable and splits into smaller nuclei
Fission reaction that will continue once initiated by high energy neutron bombarding a heavy nucleus
2 small nuclei combine to form a larger nucleus
Is mass lost during fusion?
Yes, more energy is lost than fission