Nuclear Chemistry Chapter 10

Front 1

The atomic number (Z) =

Back 1

the number of protons in the nucleus

Front 2

The mass number (A)=

Back 2

the number of protons and neutrons in the nucleus

Front 3

Isotopes are atoms of the same element

Back 3

having a different number of neutrons

Front 4

A radioactive Isotope

Back 4

called a radioisotope is unstable and spontaneously emits energy to form a more stable Nucleus

Front 5

Radioactivity is the nuclear radiation

Back 5

emitted by a radioactive isotope

Front 6

Artificial isotopes

Back 6

have been produced in the laboratory at a larger number then naturally occurring

Front 7

of the known isotopes of all elements 264 are stable

Back 7

and 300 are naturally occurring but unstable

Front 8

An alpha particle

Back 8

is a high energy particle that contains two protons and two neutrons

Front 9

A beta particle is a

Back 9

high-energy electron

Front 10

A positron is called an antiparticle

Back 10

of a beta particle, since their charges are different but their masses are the same

Front 11

Gamma rays

Back 11

are high energy radiation released from a radioactive nucleus

Front 12

Radio active decay

Back 12

is the process by which an unstable radioactive nucleus emits radiation forming a nucleus of new composition

Front 13

The sum of the mass numbers (A)

Back 13

must be equal on both sides of a nuclear equation

Front 14

The sum of the atomic numbers (Z)

Back 14

must be equal on both sides of a nuclear equation

Front 15

Alpha emission

Back 15

is the decay of a nucleus emitting an alpha particle

Front 16

The new nucleus has

Back 16

two fewer protons than the original nucleus

Front 17

Beta emission

Back 17

is the decay of a nucleus by emitting a beta particle

Front 18

The new nucleus has

Back 18

one more proton and one fewer neutron than the original nucleus the mass number is constant

Front 19

Gamma emission

Back 19

is the decay of a nucleus by emitting gamma radiation
no change in atomic number or mass number

Front 20

The half-life of a radioactive isotope

Back 20

is the time it takes for one half of the sample to decay

Front 21

the Half life of a radioactive isotope

Back 21

is a property of a given isotope and is independent of the amount of the sample, temperature and pressure

Front 22

Archaeologists use the half life of carbon-14 to determine the age of carbon containing material derived from plants and animals

Back 22

this technique is called radiocarbon dating

Front 23

The amount of radioactivity in a sample is measured by the number of nuclei

Back 23

that decay per unit time--disintegration per second

Front 24

the most common unit is a

Back 24

curie(Ci)

Front 25

and smaller units derived from the curie are

Back 25

millicurie (mCi) and
microcurie(uCi)

Front 26

A becquerel (Bq) an SI unit

Back 26

is also used to measure radioactivity 1Bq=1disintegration/second

Front 27

The rad

Back 27

radiation absorbed dose is the amount of radiation absorbed by one gram of substance. The amount of energy absorbed varies with both the nature of the substance and the type of radiation

Front 28

The rem

Back 28

radiation equiivalent for man--is the amount of radiation that also factors in its energy and potenitial to damage tissue. Using rem as a measure of radiation 1 rem of any type of radiation produces the same amount of tissue damage

Front 29

The gray

Back 29

(1gy=100rad)

Front 30

the sievert

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= 1Sv = 100 rem

Front 31

The Ld 50

Back 31

the lethal dose that kills 50% of a population = 500 rems in humans and 600 rem is fatal for the entire population

Front 32

Positron emission tomography (PET)

Back 32

scans use radioisotopes that emit positrons when the nucleus decays once formed a positron combines with an electron to form two gamma rays which create a scan of an organ

Front 33

Nuclear fission

Back 33

is the splitting apart of a heavy nucleus into lighter nuclei and neutrons

Front 34

Nuclear fusion

Back 34

is the joining together of two light nuclei to form a larger nucleus

Front 35

Nuclear fission a gram of uranium 235 releases 3.4x 10 to the 8 power kcal

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each neutron produced during fission can go on to bombard three other uranium 235 nuclei this process is called a chain reaction

Front 36

To sustain a chain reaction there must be a sufficient amount of uranium 235 this is called

Back 36

the critical mass which causes an explosion

Front 37

X-rays, CT scans, and MRIs

Back 37

these procedures are not based on nuclear reactions and do not utilize radioactivity

Front 38

X-rays are a high energy type of radiation

Back 38

called electromagenetic radiation Tissuses of different density interact differently with an x-ray beam and so a map of bone and internal organs is created on an x-ray film

Front 39

CT (computed tomography) scans

Back 39

which use x-rays provide high resolution images of the body

Front 40

MRI (magnetic resonance imaging)

Back 40

use low energy radio waves to visualize internal organs MRIs do no cell damage