Nuclear Phenomena

Question 1

some nuclei are unstable and spontaneusly emit particles and electromagnetic radiation (radioactivity) in a process called _______.
Naturally occurring spontaneous decay of certain nuclei accompanied by the emissions of specific particles
“reactant” = the parent isotope ; “parent” = daughter isoptope

Answer 1

radioactive decay

Question 2

type of radioactive decay
emissions of a Helium nucleus (alpha particle): 2 protons and 2 neutrons
mass #: decreases by 4
atomic #: decreases by 2

Answer 2

alpha decay

Question 3

type of radioactive decay
emissions of a beta particle–electron (Beta -1)
mass number: unchanged
atomic number: increases by 1

Answer 3

beta decay

Question 4

type of radioactive decay
emissions of gamma particles, which are high energy photons
lowers energy of the emitting (parent) nucleus without changing the mass number or the atomic number
happens with alpha- and beta-decay
mass number: unchanged
atomic number: unchanged

Answer 4

gamma decay

Question 5

type of radioactive decay
occurs when a positively charged particle (positron) is emitted (i.e. antielectron--has the same negligible mass but has a positive charge instead of negative)
positive beta decay
mass number: unchanged
atomic number: decreased by 1

Answer 5

positron emission

Question 6

certain unstable radionuclides are capable of capturing an inner (K or L shell) electron that combines with a proton to form a neutron
rare process
thought of as an inverse Beta - decay
mass number: unchanged
atomic number: decreased by 1

Answer 6

electron capture

Question 7

time required for half of any given quantity of a substance to react
amount of radioactive substance that remains after a period of decay will decrease exponentially with the increasing decay time
different rates for different nuclei

Answer 7

radioactive decay half-life

Question 8

Formula: Radioactive Decay Half Life: fraction of original nuclei remaining after n half lives

Answer 8

= 1/2 ^n

Question 9

Formula: radioactive decay half life: fraction of nuclei that has decayed away after n half lives

Answer 9

= 1 - (1/2)^n

Question 10

Strategy: To find the half life for a substance….

Answer 10

start with the original amount and divide by 2 until the final amount of substance has been reached
count on your fingers the number of times you divided by 2
that number is the half life for that substance