Nuclear chemistry
This presentation is the property of its rightful owner.
Sponsored Links
1 / 33

Nuclear Chemistry PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on
  • Presentation posted in: General

Nuclear Chemistry. Bravo – 15,000 kilotons. Nuclear Symbols. Mass number (p + + n o ). Element symbol. Atomic number (number of p + ). Types of Radioactive Decay. 2+. alpha production ( a ): helium nucleus beta production ( b ): neutron splits into an electron and a proton.

Download Presentation

Nuclear Chemistry

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Nuclear chemistry

Nuclear Chemistry

Bravo – 15,000 kilotons


Nuclear symbols

Nuclear Symbols

Mass number

(p+ + no)

Element symbol

Atomic number

(number of p+)


Types of radioactive decay

Types of Radioactive Decay

2+

  • alpha production (a): helium nucleus

  • beta production (b): neutron splits into an electron and a proton


Creating a reaction particle

CREATING A REACTION (α-particle)

  • On either side of the arrow, the mass number and atomic number MUST be the same (alpha-particle is always a helium nucleus)

    238U  4He + 234Th

    92 2 90

  • On the left side, mass number is 238

    • On the right side, 234 + 4 = 238

  • On the left side, the atomic number is 92

    • On the right side, 90 +2 = 92


Creating a reaction particle1

CREATING A REACTION (β-particle)

  • Both sides of the reaction still need to balance.

    • In beta-radiation, a neutron splits apart to form an electron and a proton

      234Th + 234Pa  0e

      90 91 -1

  • On the left side, mass number is 234

    • On the right side, 234 + 0 = 234

  • On the left side, the atomic number is 90

    • On the right side, 91 - 1 = 90


Alpha radiation

Alpha Radiation

Limited to VERY large nucleii.


Beta radiation

Beta Radiation

Converts a neutron into a proton.


Practice

PRACTICE

  • Each of the following compounds emits an alpha particle, write the balanced nuclear reaction

  • 222Ra

    88

  • 208Po

    84


Practice1

PRACTICE

  • Each of the following compounds emits a beta particle, write the balanced nuclear reaction

  • 14C

    6

  • 131I

    53


Types of radioactive decay1

Types of Radioactive Decay

  • gamma ray production (g):

  • positron production:

  • electron capture: (inner-orbital electron is captured by the nucleus)


Gamma radiation

GAMMA RADIATION

  • Gamma radiation does not produce any particles by itself

    • It is tied to another radioactive decay

    • Because the release of radioactive particles “frees” some energy in the nucleus, this energy takes the form of gamma radiation

      • There is a lot of energy holding the nucleus together so gamma radiation has a LOT of energy


Positron and electron capture

Positron and Electron capture

  • Positron emissions occur when a proton splits apart into a neutron and an electron

    • Therefore the mass number does not change, but the atomic number changes the element into something new

  • Electron capture occurs when a proton “captures” one of the inner valence electrons and converts it into a neutron

    • This causes the release of a powerful neutrino (as powerful as gamma radiation)


Try these

TRY THESE

  • The following go through a positron emission. Write the balanced reaction:

  • 17F

    9

  • 31S

    16


Try these1

TRY THESE

  • The following go through an electron capture. Write a balanced equation.

  • 76Kr

    36

  • 125I

    53


Another way to symbolize isotopes

ANOTHER WAY TO SYMBOLIZE ISOTOPES

  • So far we have seen one way to symbolize isotopes:

    • 17F

      9

    • 31S

      16

  • Since we know the number of protons, we can symbolize the isotope with just the mass number:

    • Fluorine-17

    • Sulphur-31


Types of radiation

Types of Radiation


Deflection of decay particles

Deflection of Decay Particles

attract

Opposite charges_________ each other.

repel

Like charges_________ each other.


Nuclear stability

NuclearStability

Decay will occur in such a way as to return a nucleus to the band (line) of stability.


Half life

HALF LIFE

  • When an isotope goes through a radioactive emission, it does so at a fairly constant rate

  • Scientists use this property to date items

  • Half-life: The time it takes for ½ of a radioactive isotope to decay to a stable form

    • Example: Carbon-14 has a half life of 5730 years

    • It takes 5730 years for ½ of radioactive Carbon-14 to decay to the stable form or Nitrogen-14

    • 14C  0e + 14N

      6 -1 7


Half life concept

Half-life Concept


How to solve half life

HOW TO SOLVE HALF-LIFE

  • Iodine-131 is used to destroy thyroid tissue in an over-productive thyroid gland. The half-life of iodine-131 is 8 days. If a hospital received a shipment of 200g of iodine-131, how much iodine-131 would remain after 32 days?


Solution

SOLUTION

  • Step 1: Find out how many ½-lives have occurred

    • (32 days/8 days for half-lives)

    • 4 half-lives

  • Step 2: Four each half-life, divide the sample by 2

    • 4 half lives = ½ x ½ x ½ x ½ = 1/16

  • Step 3: Divide the initial sample size

    • 200g/16 = 12.5g will remain


Try this

TRY THIS

  • Mercury-197 is used for kidney scans and has a half-life of 3 days. If the 32g of mercury-197 is ordered, but takes 15 days to arrive, how much would arrive with the shipment?


Sample half lives

Sample Half-Lives


A decay series

A radioactive nucleus reaches a stable state by a series of steps

A Decay Series


Nuclear fission and fusion

Nuclear Fission and Fusion

  • Fusion:Combining two light nuclei to form a heavier, more stable nucleus.

  • Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.


Energy and mass

Energy and Mass

Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:

DE = Dmc2

Dm = mass defect

DE = change in energy

c = speed of light

Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.


Fission

Fission


Fission processes

Fission Processes

A self-sustaining fission process is called a chain reaction.


A fission reactor

A Fission Reactor


Fusion

Fusion


More practice problems

MORE PRACTICE PROBLEMS

  • Nitrogen-13 emits beta radiation and decays to Carbon-13. This has a half-life of 10 minutes. You start with 2.0g of Nitrogen-13:

    • Write out the balanced nuclear reaction.

    • Calculate how much nitrogen-13 is remaining after 40 minutes.


More practice problems1

MORE PRACTICE PROBLEMS

  • Manganese-56 decays with beta radiation and has a half-life of 2.6 hours. You begin with 1mg of Manganese-56:

    • Write the balanced nuclear reaction.

    • How much manganese-56 is left after 10.4 hours?


  • Login