Atoms are the simple building block of every matter. Ionizing radiation have the right to come from rough (radioactive) atoms or it have the right to be created by machines. As turbulent atoms decay and attempt to come to be stable, the nuclei release power in the kind of ionizing radiation (alpha particles, beta particles and gamma rays). The power released is called ionizing radiation because it has actually enough power to knock strict bound electrons from the atom’s orbit. This reasons the atom to become a fee ion.

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Background info for Teachers

In the beforehand 20th century, brand-new Zealand scientist Ernest Rutherford performed an experiment whereby he shot fairly large, electrically fee particles (alpha particles) at slim gold foil. He found that many of the corpuscle passed straight through the foil, but some came off at odd angle as though they had actually been deflected. Rutherford concluded that atoms were greatly empty space, however that each contained a dense an ar — a central mass the alpha particles can not pass through. He identified that this main mass must have a hopeful charge to deflect the positively fee alpha particles. This is since like charges or magnetic fields (positive to positive or an unfavorable to negative) repel, as demonstrated once trying to location like poles that magnets with each other (north to phibìc or south to south).

Rutherford-Bohr concept of atomic Structure


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A an easy diagram of one atom.

Rutherford and Danish scientist Niels Bohr developed a way of thinking around the framework of one atom in i beg your pardon an atom looks prefer our solar system. At the facility of every atom is a nucleus, which is similar to the sun. Electron move roughly the cell core in orbits comparable to the means planets move around the sun.

Atoms covers protons, neutrons and also electrons. The nucleus includes protons and also neutrons; together these are dubbed nucleons.

Protons room positively (+) fee particles. Neutrons are electrically neutral and have no electric (0) charge. Protons and also neutrons are about 1800 times as heavy as one electron, i m sorry orbits the nucleus as a cloud. Electrons space negatively (-) charged and also balance the positive electric charge the the protons in the nucleus. Scientists’ understanding about atomic framework has ongoing to evolve. Yet, we credit transaction the Rutherford-Bohr concept of Atomic framework for providing us through a communication for expertise atomic

Determining the framework of a Neutral Atom

Neutral atoms have the same variety of protons (+) and also electrons (-). We deserve to use the periodic table, particularly the atomic number and also atomic mass because that each element, to recognize the framework of neutral atoms. The atomic number, i beg your pardon is distinctive for every element, shows the variety of protons in one atom. Because that example, every hydrogen atoms have actually 1 proton, all carbon atoms have 6 protons and also all oxygen atoms have 8 protons. Neutral atoms have actually the same variety of protons and also electrons. Therefore, hydrogen atoms have 1 proton and also 1 electron, carbon atoms have 6 protons and also 6 electrons and also oxygen atoms have 8 protons and 8 electrons.

Atoms room so small that it does not make sense to calculate their mass making use of the same units we usage every day, prefer ounces or grams. Beforehand radiation scientists occurred the atom Mass Unit (AMU) because that calculating atom mass. The atomic mass suggests the variety of nucleons (protons and also neutrons). To calculation the number of neutrons in one atom, we round the atomic mass come the nearest whole number and also subtract the atom number or number of protons from the atomic mass. For example:

Carbon: 12 (atomic mass) - 6 (atomic number) = 6. The result indicates a carbon atom has 6 neutrons, 6 protons and 6 electrons.

What holds the components of an Atom Together?

Opposite electric charges that the protons and also electrons hold the electrons in orbit around the nucleus of one atom. Within the nucleus, electromagnetic forces tend to shove the positively charged protons (and together a an outcome the entire nucleus) apart. However, the cell nucleus is hosted together by an attractive, so-called strong nuclear force between nucleons: proton-to-proton, neutron-to-neutron and also proton-to-neutron. This solid nuclear force is extremely powerful and just extends a an extremely short distance ― about the diameter the a proton or neutron. The solid nuclear force is assisted by the existence of neutrons (to assist counter the competing or repelling forces of protons) or the exchange of a particle, dubbed a meson.

Why room Some atoms Radioactive?

The fragile balance the forces amongst particles keeps the cell nucleus stable. Any readjust in the number, the arrangement, or the power of the nucleons deserve to upset this balance and cause the cell nucleus to become unstable and also create a radiation atom. Disruption of electron close come the nucleus can additionally cause one atom come emit radiation.

Can stormy Atoms come to be Stable?

As the stormy nucleus do the efforts to become stable, that emits radiation and changes right into a different facet as the number of protons changes. This procedure is referred to as radioactive decay and it proceeds until the pressures in the nucleus room balanced and also stable. Another force, so-called weak nuclear pressure is responsible because that radioactive decay. An instance of weak nuclear force is the nuclear blend reactions that power our sun and administer energy come sustain life top top Earth. Unstable atoms will attempt to end up being stable by an altering into a new isotope or element, and energy is exit in the type of ionization radiation till the pressures in the nucleus are balanced and also stable. The collection of changes that a provided radioactive facet undergoes is dubbed a degeneration chain. The complying with is an instance of a decay chain because that uranium-238.


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Source: U.S. Geological survey (USGS)

Each radioactive facet decays in ~ a unique rate. This price is well-known as a half-life; the quantity of time it takes for approximately fifty percent of the radioactive atom in a sample to degeneration into a an ext stable form. The image over indicates the radium-226 has actually a half-life of 1,602 years. So every 1,602 year approximately half of the radium-226 atom in a sample decay and adjust to radon-222 (the next facet in the degeneration chain). Note that uranium, radium and lead space metals, while radon is one inert gas under regular conditions. That is possible that as radioactive elements decay, their form (metal, gas, liquid, etc.) might change.

The half-life of slow-moving decaying elements like uranium-238 and also carbon-14 have the right to be used to recognize the age of organic matter. Radiographers likewise use half-life info to readjust film exposure times for x-rays and scans utilizing other develops of ionization radiation.

Is all Ionizing Radiation the Same?

When radioactive atoms decay, they release energy in the form of ionization radiation (alpha particles, beta particles and/or gamma rays). The energy is dubbed ionizing radiation since it has enough power to knock strictly bound electrons from an atom’s orbit. This reasons the atom to come to be a fee ion.

Alpha Particles


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picture of one alpha particle being emitted native a nucleus.

When the ratio of neutron to proton in the nucleus is also low, particular atoms reclaim the balance by create alpha particles. One alpha particle is a positively fee (+2) particle consisted of of two neutrons and also two protons. Lock are fairly heavy, high-energy particles the cannot penetrate most matter. A item of file or the dead outer layers the skin is sufficient to prevent alpha particles. Rutherford’s experiment (described above) affiliated extremely slim gold foils the were penetrated by alpha particles. Radioactive material that emits alpha particles (alpha emitters) deserve to be an extremely harmful as soon as inhaled, swallowed or absorbed into the blood stream due to the fact that internal organs are an ext directly exposed without a protective class of skin cells.

Beta Particles


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picture of a beta particle.

Beta particle emission occurs as soon as the ratio of neutrons to proton in the nucleus is also high. In this case, an overabundance neutron transforms into a proton and also an electron. The proton continues to be in the nucleus and also the electron (-1) is ejected energetically. This process decreases the variety of neutrons by one and also increases the variety of protons by one. Since the number of protons in the nucleus of one atom determines the element, the switch of a neutron come a proton actually alters the radioactive aspect (radionuclide) to a various element.

The speed of individual beta particles counts on exactly how much power they have, and also varies widely. Beta particles can be quit by a class or 2 of apparel or by a couple of millimeters that a problem such together aluminum. Lock are qualified of penetrating the skin and also causing radiation damage, such as skin burns. Similar to alpha emitters, beta emitters are most hazardous when they space inhaled or ingested.

Gamma Rays


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photo of a gamma ray.

Gamma radiation is an extremely high-energy ionizing radiation. Gamma rays have actually no mass and no electrical charge — they space pure electromagnetic energy. Gamma rays travel at the speed of light and also can sheathe hundreds to thousands of meters through the air before expending your energy. Lock can quickly penetrate obstacles such as skin and clothing. Gamma rays have actually so lot penetrating power that number of inches of a thick material choose lead or numerous feet that concrete might be required to prevent them. Gamma beam can quickly pass fully through the person body; together they pass through, it’s feasible for them to damage tissue and also DNA.

Target Audience and activity Topics

The RadTown radioactive Atom tasks are designed to help middle and also high institution students recognize the structure of one atom and describe the structural changes that happen in turbulent (radioactive) atoms together they decay. Students will learn about the Rutherford-Bohr theory of atomic Structure and also use the routine table to determine an element’s atomic structure. Students will likewise learn about the process of radioactive decay and the types of ionization radiation emitted from radiation atoms together they decay. Additionally, students will certainly learn about commonly encountered radiation elements, fission and also fusion.

NOTE: The term “radiation” supplied in the tasks generally describes ionizing radiation uneven otherwise indicated.

Activity Times

All altoalsimce.org RadTown Radiation Education tasks can be provided individually or modification and linked to develop multiple lessons. Task options permit you to customize the tasks to fit the time you have easily accessible (e.g., 1–2 class periods) and also meet the needs and interests of your students.

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The time necessary to complete activities is between 45-60 minutes, not including optional tasks or extensions.

Next Generation scientific research Standards

The principles within these task sets deserve to be supplied to support the following science standards:

PS1. Structures and also Properties of MatterPS2. Forces and Interactions

Common core State standards (CCSS)

The concepts in the Vocabulary activities align v the following

CCSS English Language Arts standards for literacy in History/Social Studies, Science, & technical Subjects:CCSS.ELA-LITERACY.RST.6-12.2 vital Ideas and also DetailsCCSS.ELA-LITERACY.RST.6-12.4 Craft and also StructureCCSS.ELA-LITERACY.L.6-12.6 Vocabulary Acquisition and Use

The ideas in the Atomic discoveries activity align with the following:

CCSS English Language Arts criter for literacy in History/Social Studies, Science, & technological Subjects:CCSS.ELA-LITERACY.SL6-12.1 Comprehension and also CollaborationCCSS.ELA-LITERACY.SL6-12.4 Presentation the Knowledge and IdeasCCSS.ELA-LITERACY.SL6-12.5 Presentation of Knowledge and also IdeasCCSS.ELA-WHST.SL6-12.1 Text species and Purposes

The ideas in the atom Math and Shorthand task align v the following:

CCSS English Language Arts criter for literacy in History/Social Studies, Science, & technological Subjects:​CSSS.ELA-Literacy.SL.6-12.1 Comprehension and CollaborationCSSS.ELA-Literacy.RST.6-12.4 Craft and also StructureCSSS.ELA-Literacy.RST.6-12.7 Integration of Knowledge and IdeasCSSS.ELA-Literacy.WHST.6-12.9 study to Build and Present KnowledgeCCSS math Standards:CCSS.MATH.PRACTICE.MP1CCSS.MATH.PRACTICE.MP2

The concepts in the strong Nuclear Forces activity align with the following:

CCSS Language Arts standards for literacy in History/Social Studies, Science, & technical Subjects:CSSS.ELA-Literacy.SL.6-12.1 Comprehension and CollaborationCSSS.ELA-Literacy.RST.6-12.7 Integration the Knowledge and also IdeasCSSS.ELA-Literacy.WHST.6-12.1 Text types and Purposes

The ideas in the atomic Stability activity align with the following:

CCSS Language Arts criter for literacy in History/Social Studies, Science, & technological Subjects:CSSS.ELA-Literacy.SL.6-12.1 Comprehension and CollaborationCSSS.ELA-Literacy.SL.6-12.5 Presentation the Knowledge and also IdeasCSSS.ELA-Literacy.RST.6-12.7 Integration that Knowledge and IdeasCSSS.ELA-Literacy.WHST.6-12.1 Text varieties and PurposesCCSS mathematics Standards:CCSS.MATH.PRACTICE.MP1CCSS.MATH.PRACTICE.MP2

The principles in the Half-Life activity align with the following:

CCSS Language Arts criter for literacy in History/Social Studies, Science, & technical Subjects:CSSS.ELA-Literacy.SL.6-12.1 Comprehension and CollaborationCSSS.ELA-Literacy.RST.6-12.4 Craft and also StructureCSSS.ELA-Literacy.RST.6-12.7 Integration that Knowledge and IdeasCCSS.ELA-Literacy.WHST.6-12.1 Text varieties and PurposesCSSS.ELA-Literacy.WHST.6-12.9 research to Build and also Present KnowledgeCCSS math Standards:CCSS.MATH.PRACTICE.MP1CCSS.MATH.PRACTICE.MP2

The ideas in the Radioactive decay Chain activity align v the following:

CCSS Language Arts requirements for proficiency in History/Social Studies, Science, & technological Subjects:CSSS.ELA-Literacy.SL.6-12.4 Presentation of Knowledge and IdeasCSSS.ELA-Literacy.RST.6-12.4 Craft and StructureCSSS.ELA-Literacy.RST.6-12.7 Integration the Knowledge and also IdeasCCSS math Standards:CCSS.MATH.PRACTICE.MP1CCSS.MATH.PRACTICE.MP2