Nuclear chemistry equations

Radioactive Decay

Radioactive decay is the process by which an atomic nucleus undergoes a spontaneous change, emitting an alpha particle or beta particle and/or a gamma ray.

 Radioactive decay is a natural process that takes place in the air, water, and soil at all times. The decay of isotopes such as uranium-238, radium-226, radon-222, potassium-40, and carbon-14 produce radiation that poses an unavoidable and, probably, minimal hazard to human health. Scientists have also learned how to convert stable isotopes to radioactive forms. The radioactive decay of these isotopes has been added to the natural background radiation from naturally radioactive materials.

Types of Radioactive Decay

Alpha Decay

An element in alpha decay loses two neutron and two protons. This moves the element back two places on the periodic table.—most common in elements with atomic number greater than 83--  It is not particularly strong, but the alpha particles can knowck atoms off of molecules

Beta Negative Decay

Increases proton by one and LOSS of one neutron. The smaller particles make it more penetrating than alpha but less penetrating than gamma decay. Penetrates through one cm of flesh before they are stopped.

Gamma Decay

Occurs when the parent isotope falls into a lower energy state. It  is the most strong/penetrating. Gamma radiation emits photons that can pass through the body and causee damage by ionizing the molecules in their way.

Positron Emission [Beta Positive Decay]

A positon is like an electron, except it has a positive charge. This is a reaction when the radiation produces positrons

Electron Capture

The nucleus captures one of its atoms inner shell electrons, so the atomic number is reduced by one. This electron joins with a proton in the nucleus to form a neutron.

All elements with an atomic number over 83 are considered radioactive. Radioactivity can be measured using a geiger counter.

Different types of Radiation

ALPHA RADIATION

Heavy, short range, ejected helium nucleus. It can’t penetrate human skin. But if it is inhaled, swallowed, or absorbed through open wounds, it can be harmful.

Geiger-Mueller probe can detect the presence of alpha radiation. Travels a short distance.

radium, radon, uranium, thorium.

BETA RADIATION

Travels a few feet into the air, can penetrate a  very thin layer of the skin If if beta radiation are in contact with the skin for a long time they can cause injury.

Difficult to detect, clothing provides a little protection to the skin

strontium-90, carbon-14, tritium, and sulfur-35. difficult-to-detect beta emitters are hydrogen-3 (tritium), carbon-14, and sulfur-35.

GAMMA & X RAYS

Gamma Travel many feet in the air and deep into human tissue. They are known as “penetrating” radiation

X rays – similar to gamma,

Electromagnetic radiation=UV rays, radiowaves, visible light according to energy levels

During radioactive decay, gamma radiation or x rays frequently accompany the mission of alpha amnd beta radiation.

Gamma Emitters: iodine-131, cesium-137, cobalt-60, radium-226, and technetium-99m.

Radioactivity...

What is Radioactivity?

                -revolutionized physics, gradually transmuted into nuclear physics

                -changed the ideas about matter and energy

                -advaned medicine and energy production

                -world politics forever affected, and brought a slew of new health hazards

1896: science first introduced an invisible radiation that could penetrate opaque bodies (Xrays)

Antoine Henri Becquerel- physicist who tested phosphorescent minerals. The first mineral to produce results; initially it was thought that sunlight was needed to produce an image using phosphorescence but he found that he didn’t need the sun. creating the rays only required uranium, Becquerel believed he’d discovered an invisible light. Found that uranium rays had electrical effects.

Maria Curie was working on a doctoral thesis, and wanted to search for elements that gave off invisible rays, called this “radioactivity”. She used ionization to test minerals. In this process she worked tirelessly and eventually uncovered the existence of two new elements: polonium and radium. These also created invisible rays.

                Curie’s discoveries led to many people using the radiation they emitted. Scientists doubted Curie but her discoveries gave way to new methods and instrumentation, from which she was able to determine the properties of her new elements.

Found that three types of rays were emitted in this process of radiation: alpha, beta, and gamma rays

Scientists could not figure out what the energy source of radioactivity. Seemed to violate the principle of conservation energy (the principle that the total energy of any isolated system is constant and independent of any changes occurring within the system)

Sparked ideas about atomic transmutation; led to a discovery that atomic disintegration was a random occurrence, which altered physicist’s premise about causality in nature, which influenced the way they perceived many aspects of history and science. Later radioactivity was used to treat illnesses, as it was learned that it could  cause mutations in plants and animals.

Madame Curie’s example in her research and discoveries surrounding radioactivity inspired many women to become involved in researching the field

1930s—radioactivity became the study of nuclear physics

Nuclear physics=ethical, social, political controversy.

How is Radioactivity Detected?

A human can not detect radiation with their senses. Varieties of handheld and laboratory instruments are available for detecting and measuring radiation.

http://hps.org/publicinformation/ate/faqs/radiationdetection.html

Human senses cannot detect radiation. People have to use specialized instruments….

Geiger Counter using a Geiger-Mueller Probe

                -uses high voltage to create a n electrical pulse that interacts with the gas contained in the instrument. The pulses are converted to a reading on the meter of the instrument.

MicroR Meter &Sodium Iodide Detector

                -a crystal of sodium iodide creates a pulse of light when radiation interacts with it. The pulse is converted to an electrical signal which translates to a reading on the meter of the instrument. The pulse of light is proportionate to the amount of light and energy deposited in the crystal.

Portable Multichannel Anallyzer

An affordable and common way to measure. This is the same machine described above, used with a multichannel analyzer. Automatically displays the radioactive materials present.

Ionization Chamber

X ray or gamma radiation creates a current in this chamber of air, which is then displayed on a meter.

Neutron REM Meter

Radon Detector

Radioactive decay is when an unstable atom disintegrates and is accompanied by radiation emission. Once the atom becomes stable again, it ceases to emit radiation. Because of this, radioactive sources become weaker with time. Eventually this allows atoms to become non-radioactive.

The half life of radiation is when the intensity of the source progresses from its 100% fullest to 50% intensity.

Radiation and Age

Radiocarbon dating: the earth’s upper atmosphere is constantly exposed to cosmic radiation, so scientists can use the unstable isotope of carbon (known as carbon 14) and this becomes a part of the molecular structure of everything on earth, because it attaches itself to complex organisms fixed in the biosphere. Scientists can determine how much of this element is present in an organism (includes fossils and such) so they can determine how old something is by determining its half life.

Tools Used to Detect Radiation

Liquid Scintillation

Proportional Counter

Multichannel Analyzer System

Nuclear Fission v. Nuclear Fusion

Comparison Chart


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	NUCLEAR FISSION	NUCLEAR FUSION
Definition:	Fission is the splitting of a large atom into two or more smaller ones	Fusion is the fusing of two or more lighter atoms into a larger one
Conditions:	Critical mass of the substance and high-speed neutrons are required	High density, high temperature environment is required
Energy Requirement:	Takes little energy to split two atoms in a fission reaction	Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion
Natural Occurrence of the Process:	Fission reaction does not normally occur in nature	Fusion occurs in stars, such as the sun
By Products of the Reaction:	Fission produces many highly radioactive particles	Few radioactive particles are produced by a fusion reaction, but if a fission “trigger” is used, radioactive particles will result from that
Energy Ratios:	The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion	The energy released by fusion is three to four times greater than the energy released by fission
Nuclear Weapon:	One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb	One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to “trigger” a fusion reaction

http://www.diffen.com/difference/Nuclear_Fission_vs_Nuclear_Fusion

What is Nuclear Chemistry?

Nuclear chemistry is a subfeild of chemistry that deals with radioactivity, nuclear processes and nuclear properties. A particular division of nuclear chemistry is the process involved with splitting and combining of atoms to make new substances and energy.