Nuclear chemistry
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Chemistry I – Chapter 25 Chemistry I Honors – Chapter 19 ICP – Chapter 18. Nuclear Chemistry.

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Nuclear Chemistry

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Nuclear chemistry

Chemistry I – Chapter 25

Chemistry I Honors – Chapter 19

ICP – Chapter 18

Nuclear Chemistry

SAVE PAPER AND INK!!! When you print out the notes on PowerPoint, print "Handouts" instead of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!


Radioactivity

Radioactivity

  • One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of________ (1876-1934).

  • She discovered________, the spontaneous disintegration of some elements into smaller pieces.


Nuclear reactions vs normal chemical changes

Nuclear Reactions vs. Normal Chemical Changes

  • Nuclear reactions involve the nucleus

  • The nucleus opens, and protons and neutrons are rearranged

  • The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together – called binding energy

  • “Normal” Chemical Reactions involve electrons, not protons and neutrons


Mass defect

Mass Defect

  • Some of the mass can be converted into energy

  • Shown by a very famous equation!

    E=mc2

Energy

Mass

Speed of light


Types of radiation

Types of Radiation

  • Alpha (ά) – a positively charged helium isotope - we usually ignore the charge because it involves electrons, not protons and neutrons

  • Beta (β) – an electron

  • Gamma (γ) – pure energy; called a ray rather than a particle


Other nuclear particles

Other Nuclear Particles

  • Neutron

  • Positron – a positive electron

  • Proton – usually referred to as hydrogen-1

  • Any other elemental isotope


Penetrating ability

Penetrating Ability


Balancing nuclear reactions

Balancing Nuclear Reactions

  • In the reactants (starting materials – on the left side of an equation) and products (final products – on the right side of an equation)

  • Atomic numbers must balance

  • and

  • Mass numbers must balance

  • Use a particle or isotope to fill in the missing protons and neutrons


Nuclear reactions

Nuclear Reactions

  • Alpha emission

Note that mass number (A) goes down by 4 and atomic number (Z) goes down by 2.

Nucleons (nuclear particles… protons and neutrons) are rearranged but conserved


Nuclear reactions1

Nuclear Reactions

  • Beta emission

Note that mass number (A) is unchanged and atomic number (Z) goes up by 1.


Other types of nuclear reactions

207

207

Other Types of Nuclear Reactions

Positron (0+1b): a positive electron

Electron capture: the capture of an electron


Learning check

Learning Check

What radioactive isotope is produced in the following bombardment of boron?

10B + 4He ? + 1n

5 2 0


Write nuclear equations

Write Nuclear Equations!

Write the nuclear equation for the beta emitter Co-60.


Artificial nuclear reactions

Artificial Nuclear Reactions

New elements or new isotopes of known elements are produced by bombarding an atom with a subatomic particle such as a proton or neutron -- or even a much heavier particle such as 4He and 11B.

Reactions using neutrons are called g reactions because a g ray is usually emitted.

Radioisotopes used in medicine are often made by g reactions.


Artificial nuclear reactions1

Artificial Nuclear Reactions

Example of a g reaction is production of radioactive 31P for use in studies of P uptake in the body.

3115P + 10n ---> 3215P + g


Transuranium elements

Transuranium Elements

Elements beyond 92 (transuranium) made starting with an g reaction

23892U + 10n ---> 23992U + g

23992U ---> 23993Np + 0-1b

23993Np ---> 23994Pu + 0-1b


Nuclear fission

Nuclear Fission


Nuclear fission1

Nuclear Fission

Fission is the splitting of atoms

These are usually very large, so that they are not as stable

Fission chain has three general steps:

1. Initiation. Reaction of a single atom starts the chain (e.g., 235U + neutron)

2. Propagation. 236U fission releases neutrons that initiate other fissions

3. ___________ .


Stability of nuclei

3115P

21H, 63Li, 105B, 147N, 18073Ta

199F

Stability of Nuclei

  • Out of > 300 stable isotopes:

N

Even

Odd

Z

157

52

Even

Odd

50

5


Band of stability and radioactive decay

Band of Stability and Radioactive Decay


Representation of a fission process

Representation of a fission process.


Nuclear fission power

Nuclear Fission & POWER

  • Currently about 103 nuclear power plants in the U.S. and about 435 worldwide.

  • 17% of the world’s energy comes from nuclear.


Figure 19 6 diagram of a nuclear power plant

Figure 19.6: Diagram of a nuclear power plant.


Nuclear fusion

Nuclear Fusion

Fusion

small nuclei combine

2H + 3H 4He + 1n +

1 1 2 0

Occurs in the sun and other stars

Energy


Nuclear fusion1

Nuclear Fusion

Fusion

  • Excessive heat can not be contained

  • Attempts at “cold” fusion have FAILED.

  • “Hot” fusion is difficult to contain


Half life

Half-Life

  • HALF-LIFE is the time that it takes for 1/2 a sample to decompose.

  • The rate of a nuclear transformation depends only on the “reactant” concentration.


Half life1

Half-Life

Decay of 20.0 mg of 15O. What remains after 3 half-lives? After 5 half-lives?


Kinetics of radioactive decay

Kinetics of Radioactive Decay

For each duration (half-life), one half of the substance decomposes.

For example: Ra-234 has a half-life of 3.6 daysIf you start with 50 grams of Ra-234

After 3.6 days > 25 grams

After 7.2 days > 12.5 grams

After 10.8 days > 6.25 grams


Learning check1

Learning Check!

The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 39 hours?


Effects of radiation

Effects of Radiation


Geiger counter

Geiger Counter

  • Used to detect radioactive substances


Radiocarbon dating

Radiocarbon Dating

Radioactive C-14 is formed in the upper atmosphere by nuclear reactions initiated by neutrons in cosmic radiation

14N + 1on ---> 14C + 1H

The C-14 is oxidized to CO2, which circulates through the biosphere.

When a plant dies, the C-14 is not replenished.

But the C-14 continues to decay with t1/2 = 5730 years.

Activity of a sample can be used to date the sample.


Nuclear medicine imaging

Nuclear Medicine: Imaging

Thyroid imaging using Tc-99m


Food irradiation

Food Irradiation

  • Food can be irradiated with g rays from 60Co or 137Cs.

  • Irradiated milk has a shelf life of 3 mo. without refrigeration.

  • USDA has approved irradiation of meats and eggs.


Practice

practice

  • Nuclear reaction ws

  • http://www.chemistrygeek.com/chem1.htm


Question 1

Question 1

  • a. 1s22s22p63s23p8

  • b. 1s22s22p63s23p64s2

  • c. 1s22s22p63s23p63d2

  • d. 1s22s22p83s23p6


Answer

answer

  • Which is the electronic configuration of calcium?

  • a. 1s22s22p63s23p8

  • b. 1s22s22p63s23p64s2

  • c. 1s22s22p63s23p63d2

  • d. 1s22s22p83s23p6


Question 2

Question 2

  • The half-life of a radioactive isotope is 20 minutes. What is the total amount of 1.00 g of sample of this isotope remaining after 1 hour?

  • a. 0.500 g

  • b. 0.333 g

  • c. 0.250 g

  • d. 0.125 g


Answer1

answer

  • The half-life of a radioactive isotope is 20 minutes. What is the total amount of 1.00 g of sample of this isotope remaining after 1 hour?

  • a. 0.500 g

  • b. 0.333 g

  • c. 0.250 g

  • d. 0.125 g


An isotope contains

An isotope contains:

  • Same number of e- different number of ions

  • Same number of protons, different number of neutrons

  • Same number of neutrons, different number of protons

  • Same number of protons, different number of e-


Answer2

answer

  • Same number of e- different number of ions

  • Same number of protons, different number of neutrons

  • Same number of neutrons, different number of protons

  • Same number of protons, different number of e-


Aluminum is a

Aluminum is a

  • Metal

  • Non metal

  • Noble gas

  • None of the above


Answer3

answer

  • Metal

  • Non metal

  • Noble gas

  • None of the above


H has how many valence e

H has how many valence e-?

  • 2

  • 3

  • 1

  • 0


Answer4

answer

  • 2

  • 3

  • 1

  • 0


Al has a higher ionization energy than s

Al has a higher ionization energy than S?

  • True

  • false


Answer5

Answer

  • false


The symbol for tin is

The symbol for tin is?

  • ?


Answer6

Answer

  • Sn


Group 8 on the periodic table is also known as

Group 8 on the periodic table is also known as

  • The alkali metals

  • The halogens

  • The noble gases

  • I have no idea


Answer7

answer

  • The noble gases


How many electrons must an atom have on its outer shell to be stable

How many electrons must an atom have on its outer shell to be stable

  • ?


Answer8

Answer

  • 8


The element si is

The element Si is:

  • A metal

  • A nonmetal

  • A metalloid

  • Not an element


Answer9

Answer

  • metalloid


Last one

Last one…

  • Draw the bohr model for He on your board


It should look like this

It should look like this


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