week 6 adapt
Which of the following procedures in healthcare involve the use of radiation to take images?
Radiation is used extensively in healthcare for imaging as well as treatment. CT scans and X-rays both involve radiation.
Nuclear Medicine: Nuclear Imaging
Radioactive materials have many real world uses in the field of healthcare. These materials provide us with important diagnostic tools and treatments, and like any tools, must be treated with respect and used responsibly. In healthcare, the largest use of radioactive materials is in imaging; an area known as nuclear imaging. PET (positron emission tomography) scans X-ray imaging Contrast agents (radioactive materials injected to increase the contrast of tissues when imaging)
Select all that would be considered sources of ionizing radiation.
Recognizing the sources of radiation in your day to day life helps you to make informed decisions about exposure. CT scans and radon gas are both sources of ionizing radiation.
Determine if each of the following electromagnetic radiation types is ionizing or non-ionizing:
Shorter wavelengths of light are high in energy and able to ionize while longer wavelengths are lower in energy and not able to ionize. Infrared and radio waves are both non-ionizing, while gammy rays are ionizing.
As previously mentioned, all light is a form of radiation. Light exists as both a particle and a wave and, like all other sources of electromagnetic radiation, consists of photons. The light that we see, known as visible light, is only part of the light that we are exposed to. Light exists as a spectrum of wavelengths with shorter wavelengths being higher in energy. On the long wavelength end, we have radio waves, cell phone waves, microwaves, and infrared radiation. These are all non-ionizing. Next we have visible light, which is the type of light that we are able to see as humans. This radiation is not ionizing. Higher in energy than visible light, with have ultraviolet (UV light), followed by X-rays and gamma rays. At the high end of the UV scale and beyond, this radiation is ionizing. The spectrum above illustrates the electromagnetic spectra of light. This light is emitted from a variety of sources with examples given below:
Source / Electromagnetic sources released Sun / Entire spectra Incandescent bulbs / Visible and partially into infrared White LED / Visible Tanning bed bulbs / Ultra violet Microwave ovens / Microwaves
The reason for this different penetrative ability is largely due to the speed at which each type of radiation is traveling as well as the mass of the particles. Because of these differences, alpha particles can be blocked by a sheet of paper while gamma rays require a few cm of lead, a great radiation blocking material, to fully block them.
Speaking of blocking of radiation, lead is great material for shielding from radiation. Lead is the gold standard for blocking radiation and is used extensively in the containment of radioactive materials.
Monosaccharides, Disaccharides, and Polysaccharides
The basic carbohydrate unit is the monosaccharide. Monosaccharides are simple sugars that have an unbranched chain of 3-8 carbon atoms and are classified as either an aldose or a ketose. Aldoses contain an aldehyde, whereas ketoses contain a ketone. Most of the time, monosaccharides exist in a ring structure that has formed when the carbonyl and a hydroxyl group on the same molecule have reacted. Aldoses will typically form hexagon cyclic structures, and ketoses will typically form pentagon cyclic structures. By remembering the mnemonic "Mona Gladly Fruits the Gallon" you can remember three common monosaccharides: Monosaccharides are glucose, fructose, and galactose. Glucose aldose Fructose ketose Galactose aldose These three carbohydrates are isomers; they have the same molecular formula, but differ in the arrangement of the functional groups. They all have the formula C6H12O6. A common monosaccharide is glucose. Glucose is an aldose and is found in many sources, and is the major carbohydrate of energy. This molecule is used in the first step of the energy making process, and many energy storage polymers are made from glucose monomers. Glucose forms a six-membered cyclic hexagon in solution. Cyclic structure of glucose Fructose is commonly found in fruits, and is sometimes called fruit sugar. When combined with glucose, fructose will be used to form the disaccharide sucrose. In nature, this forms a five-membered pentagon ring. Cyclic structure of fructose Galactose is also called "cerebrose" or "brain sugar." When combined with glucose, galactose will be used to form the disaccharide lactose. Galactose will form a hexagon in solution, similar to glucose.
Other Uses of Radiation
The examples we are exploring in this lesson are only a few of the many uses of radiation in our world. A few more examples of radiation used in our day to day lives include: Smoke detectors -Smoke detectors use americium as a source of alpha particles between an emitter and a detector -When smoke is present, the flow of radiation is disrupted and the alarm goes off. Irradiation of food -Irradiation of food, typically with gamma radiation, kills microorganisms so that the food stays fresher longer -Does not cause the food to become radioactive Airport scanners -X-Rays are used to check baggage for contraband -Geiger counters are also used to check that no radioactive materials are being brought onto planes Each of these is an example of the many ways that we use radiation in our day to day lives. One take home lesson is that radiation is a useful tool; however, we should be aware of our exposure and treat this tool with respect.
Nuclear Medicine: Therapy
The field of nuclear medicine has allowed for advances in the treatment of many medical conditions. Radiation therapy is a general term for using radiation to treat an ailment. Examples of this include: Gamma radiation used to eliminate tumors noninvasively Brachytherapy (inserting "seeds" into tissue) used mainly in the treatment of prostate cancer Iodine-131 used to treat hyperthyroidism or thyroid cancer As radiation therapy exposes a patient to far more ionizing radiation than a simple medical scan, the risks of these procedures are greater. Because of this risk, radiation therapy is generally limited to serious medical concerns such as cancer and other life threatening conditions. Additionally, there is a limit to the amount of radiation a body can safely receive in a lifetime and each patient's radiation exposure, both overall and per area of the body, are tracked. Radiation therapy can also require the patient to take precautions around others due to the fact that radiation therapy, depending on the type used, can make an individual shed radiation. Individuals undergoing radiation therapy are often asked to avoid prolonged exposure to other individuals, especially children, in the time frame they are undergoing therapy. Healthcare workers must also be aware of the risks when administering nuclear medicine. Healthcare workers use radiation badges to track exposure, administer treatments only in specific rooms, and use specialized personal protective equipment.
Select all processes which cause a decrease in the atomic number of an isotope.
The main ways to decrease atomic number are the removal of protons from the nucleus or the conversion of a proton to a neutron. This could occur via alpha decay, beta positron decay, and electron capture.
As we see above, our atomic number (number of protons) increases (from 8 to 9) for the oxygen, transmuting the oxygen into a fluorine nucleotide. This is consistent with our understanding that a neutron becomes a proton during beta decay. We also see again our conservation of both mass and charge as the top number has a total of 19 on both sides while our bottom number has a total of 8 on both sides. Once again, we know that the nucleotide product is F as the periodic table tells us that any atom with an atomic number of 9 is an atom of F.
The model below shows the beta decay of Oxygen-19. As we can see, a neutron becomes a proton by releasing an electron. In the process, the atomic number is increased by one while leaving the mass number unchanged. We see that for the atomic number, we have 8-(-1) =9.
Radioactive Decay
The reason radioactive material is radioactive is that such material contains unstable isotopes. Remember the term isotope refers to atoms of a specific element that differ based on their mass number. Radioactive decay: The spontaneous process by which an isotope with an unstable nucleus decays by re-releasing matter and/or energy from the nucleus. The three main types of radioactive decay are: Alpha decay Beta decay Gamma decay There are two types of beta decay, electron and positron. All of these are forms of ionizing radiation. The table below shows the types of radiation released from each type of decay as well as the type, mass, and charge.
The Second Law of Thermodynamics
The second law of thermodynamics tells us about how energy in the universe behaves in terms of flow and organization. The amount of entropy in an isolated system irreversibly increases over time. This law tells us that the amount of entropy, or disorder, in the universe is constantly increasing. An important reason for this is that heat spontaneously and irreversibly transfers from a hot body to a cold body. An example that illustrates both of these points is a cup of hot coffee sitting outside on a cold winter's day. At first, the heat is localized into the area of the liquid in the cup; however, the heat quickly begins to disperse into the surrounding environment spontaneously. Over time, the coffee in the cup will have the same temperature as the surrounding environment as the temperatures even out. In this way, we see that: Heat was spontaneously and irreversibly transferred from a higher temperature system area to the lower temperature surroundings. Disorder increased as the localized heat spread through the surroundings.
Beta Decay: Electron
There are two types of beta decay: electron and positron. The key difference between the two is that the electron beta particles have a negative charge while the positron beta particles have a positive charge. We will start by studying the electron version of beta decay. In electron beta decay, a neutron is converted to a proton and emits an electron in the process. Please note that this electron is not one of the electrons outside the nucleus, and instead is emitted directly from the nucleus. As you likely remember from prior lessons, an electron has a -1 charge and a small mass of ~0 and thus the beta particle is expressed as:
When an electron is emitted from a neutron, the neutron becomes a proton. The reason behind this is similar to the reason that atoms become positively charged when emitting electrons: when negative charge is lost, a system becomes more positive. Therefore, when a neutron emits a negative charge, it gains a positive charge and is thus a proton (neutrons cannot have + charges).
This means that in beta decay: a neutron becomes a proton by emitting an electron. An example of electron beta decay appears below as oxygen-19 decays.
Radiation that has mass and can cause atoms and molecules to become charged would be classified as:
Understanding the categories of radiation can help us to understand the properties of different types of radiation. Ionizing and particulate are both classifications of radiation that can cause atoms and molecules to become charged.
This type of radiation cannot remove electrons from atoms or molecules:
Understanding the categories of radiation can help us to understand the properties of different types of radiation. Non-ionizing radiation does not remove electrons.
Sort the following types of radiation in regard to their ability to penetrate the human body from top (most) to least (bottom).
Understanding the penetrative properties of various types of radiation can help us make important safety choices. The most penetrating type of radiation is gamma, while the least is alpha.
Water molecules are produced in condensation reactions, when bonds are formed.
Water molecules are used to break bonds in hydrolysis reactions.
Other Sources of Radiation
We are exposed to radiation at all times. You are exposed to radiation within your body, in the environment, and even from space. Some of this radiation is ionizing radiation. The good news is that our bodies are constantly on the lookout for radiation damage and can heal from this in most cases. In addition to the sources of radiation we have covered thus far, other sources of radiation we are exposed to on a day to day basis are: Radon gas: Radon is a radioactive gas that is found within the earth's crust. Radon produces ionizing radiation and is a leading cause of lung cancer. As this gas can easily leak into homes, radon testing and mitigation can minimize exposure. Out of all of the sources of radiation we have studied, this is one of the most dangerous ones that we can most easily mitigate. Cosmic radiation: These radioactive subatomic particles come from the sun, cosmic events in the galaxy such as supernovas, and even from outside of the galaxy. Most of these pass harmlessly through the earth and our bodies. You are exposed to more cosmic radiation if you fly frequently as higher altitudes are less protected by our atmosphere. Internal radiation: A very small percentage of the isotopes in our bodies (such as potassium-40) are radioactive. This means that each person is slightly radioactive. This radioactive material comes from food and water we ingest. For example, bananas, due to their high potassium content, have slightly elevated levels of potassium-40. You may notice that nuclear power plants are not on this list. This is because, if functioning correctly, a nuclear power plant does not release very much radiation. Radioactive waste, if properly stored, also does not result in a significant contribution to overall exposure.
171^ 80 Hg undergoes alpha decay forming an alpha particle and
We can determine the effect on the decay product by following the Law of Conservation of Mass. When 171/80Hg undergoes alpha decay, an alpha particle and 167/78Pt is formed.
If Magnesium-21 undergoes beta positron decay, I would expect the products of this decay to be a positron and a
We see a decrease of one for the atomic number in positron decay with no change in the mass number.
Condensation Reactions
When polymers are built from monomers (anabolism) they undergo condensation reactions. Condensation reactions in natural polymers occur between functional groups such as carboxylic acids, alcohol, and amines. The primary by-product of this reaction is a small molecule, often water. The two functional groups will react with each other, releasing a molecule of water. This leaves unpaired atoms, which then bond with each other to fulfil their octet valence electron requirements. The only portion of the molecule that is affected by the reaction are the atoms involved in forming water; all other atoms in the molecule retain their bonds. As shown in previous lessons, condensation reactions form new functional groups such as ethers and esters. The condensation of two alcohols forms an ether; the condensation of an alcohol and a carboxylic acid forms an ester. Condensation reaction of ethanoic acid and butanol to form an ester. The hydroxyl groups of the alcohol and carboxylic acid will react to release one molecule of water; the remaining oxygen will form a new bond to the carbon chain, joining the ethanoic acid and butanol carbon chains. Similarly, the basic amine can condense with the acidic carboxylic acid, releasing water in its condensation reaction. This forms an amide bond, which is how proteins are formed from amino acids.Condensation reactions always have at least one monomer as a reactant, and always have water as a product and a combination of the molecules, the polymer, as the second product. The example above shows two monomers reacting to form a dimer (meaning "two parts"); however, a longer polymer chain may also react via condensation with a monomer. This happens in the formation of long-chain polymers, which are built by adding one monomer at a time.
Hydrolysis Reactions
When polymers break down during catabolism, hydrolysis reactions occur. In hydrolysis reactions, a molecule of water is used to break a bond, separating the monomers. These reactions are essentially the reverse of condensation. To complete this reaction, the electrons on the electronegative oxygen in water will attach to the polymer. This attachment causes the existing bond between the monomers to break, releasing the two separated monomers. This follows the law of conservation of mass, by rearranging the bonding of the atoms present to form new products. In these reactions, the substrates are polymers and water, which then form monomers as the product.
Ionizing radiation is higher in energy with shorter wavelengths while non-ionizing radiation is lower in energy with longer wavelengths.
X-rays and Gamma rays are ionizing; Microwaves, infrared, visible light, and radio waves are non-ionizing.
Dimers are made from two monomers,
so they are larger than monomers.
The following monomer is involved in a condensation reaction. Click the plus to see the portion that will remain unchanged.
Alcohol, amine, and carboxylic acid groups can combine in condensation reactions. In this example, the -OH of the hydroxyl group will be used in the condensation reaction, and the remainder of the molecule will remain unchanged.
Classify the molecules as aldoses or ketoses:
Aldoses contain an aldehyde functional group on the top carbon; ketoses will contain a ketone functional group on a middle carbon. Glucose and Galactose are aldoses, Fructose is a ketose.
As we see here, the Te released an alpha particle. In the process, the mass number of the Te isotope decreased by 4 and the atomic number decreased by 2. The atomic number of the new nucleotide decreased by 4 from 104 to 100. Since the atomic number (number of protons) is what determines the atom we have, the resulting nucleotide is now Sn instead of Te. We know this because the nucleotide formally known as Te now has 50 protons and, looking at the element with 50 protons on the periodic table, we see that we now have Sn. This process of converting from one element to another is called transmutation. We see transmutation occur in most types of radioactive decay. Below is a model of an alpha decay. Note how the alpha particle is emitted, leaving behind a new nucleotide. Please note that an alpha particle is always 2 protons and 2 neutrons as seen below. ^4 2 α
Alpha decay is unique in that this is the only type of radioactive decay we are studying that changes the mass number of the resulting nucleotide. This illustration below shows the original particle undergoing alpha decay and emitting an alpha particle (the small particle), leaving a new nucleotide (the circle particle).
Ionizing and Non-ionizing Radiation
Another way to categorize radiation is as ionizing or non-ionizing radiation. As you may recall, ions are charged atoms or molecules. Ionizing radiation is radiation that is able to cause atoms or molecules to become charged by removing electrons. Non-ionizing radiation is not able to cause the formation of ions as types of radiation that fall into this category cannot remove electrons from atoms or molecules. The reason that some radiation is ionizing and others are non-ionizing comes down to energy. High energy radiation is better able to cause ionization than lower energy forms. This is because it takes energy to remove electrons. These categories of radiation overlap with the other categories of radiation: particulate and electromagnetic. As an example, visible light is a type of electromagnetic radiation that is non-ionizing while X-Rays are a type of electromagnetic radiation that is ionizing.
Type of Decay Radiation released Mass of particle Charge of Particle Type of Radiation
Beta (positron) ^0 1β+ ~0 +1 Particulate
Determine the products of the beta electron decay of Vanadium-52 (select all that apply): 52/23 V
Beta decay increases the atomic number by 1.
Type of Process Effect on mass number Effect on atomic number
Beta electron No change Increase by 1
Type of Process Effect on mass number Effect on atomic number
Beta positron No change Decrease by 1
Monomers and Polymers
Biochemistry is the study of how organisms use molecules for life processes. Many of the molecules used to build cells are polymers. The word polymer means "many parts." These polymers are formed from monomers, meaning "one part." Monomers are small units of the larger polymers. As part of normal processes called metabolism, your body can build polymers (anabolism) or break polymers into their components (catabolism). Every time you eat a delicious meal, your body is breaking down the large polymers to recycle them into monomers. Your body's chemistry can then rearrange those monomers to form different polymers. For example, a toy brick model of a car would be considered a polymer because it is made of many monomers. The monomers are the individual toy bricks. If the car is torn down (catabolized), the monomers can then be used to build a brick castle instead (anabolism). Polymers are found in our everyday lives. Items such as polystyrene, also known as Styrofoam, are made from styrene monomers. Silk is a polymer made naturally from amino acid monomers, as is cotton. Rubber is a polymer made from the monomer isoprene. Polymers found in your body that will be discussed in later lessons are: -carbohydrates, made of monosaccharide monomers -proteins, made of amino acid monomers -nucleic acids, made of nucleotide monomers These are the macromolecules ("macro" meaning "large").
During a type of radioactive decay, the atomic number of an isotope increases by one while the mass number is unchanged. I would expect that this is caused by
By understanding what is happening on a subatomic level, we can better predict what is occurring in a specific radioactive decay process. When the atomic number increases by one while the mass number is unchanged, a neutron has become a proton.
An proton absorbs an electron. What effect would you predict this to have in an unstable isotope?
By understanding what is happening on a subatomic level, we can better predict what is occurring in unstable isotopes. If a proton absorbs an electron in an unstable isotope, you would see a decrease in the atomic number.
Ionizing radiation is used for mainly imaging and radiation therapy in healthcare.
CT scans are a type of imaging used in healthcare and is ionizing.
Structures and Properties of Carbohydrates
Carbohydrates are an important source of energy in our bodies. They contain many -OH groups (alcohol groups, also known as hydroxyl groups) and contain a carbonyl functional group: either aldehyde or a ketone. We see examples of these in the world around us. Examples include table sugar, starch, and even wood. The simplest of these carbohydrates are known as monosaccharides. These simple sugars can be linked together to form more complex carbohydrates: disaccharides and polysaccharides. Carbohydrates are found throughout cells, both inside and outside. This class of macromolecules is used for energy, energy storage, structure, and cell recognition. These molecules are water soluble and can move into cells to provide energy. When formed into long chain polymers, they can store energy for future use in the cell such as starch in plants, and glycogen in humans. In plant cells, carbohydrate polymers called cellulose form rigid protective structures called the cell wall. Human cells do not contain cell walls, but sugar molecules are found on the surface of our cells as recognition such as on the surface of blood cells; these carbohydrate markers give us blood types A, B, AB, and O. When incompatible blood types are mixed, the blood will coagulate. Image of a cell wall in plants. This cell wall contains the carbohydrate polymer cellulose, which is rigid and provides structure to plant cells. Sugar molecules on the surface of red blood cells give the different blood types: A, B, AB, and O.
Select all that apply. Carbohydrates can be used for which of the following cellular functions:
Carbohydrates are used for cell recognition such as ABO blood groups, energy storage such as glycogen, used as energy such as glucose, and cell walls such as polysaccharides. They would not be used for information storage.
Select the letter next to the circled portion of the molecule that will react in a condensation reaction.
Carboxylic acids (-COOH) can react in condensation.
Which portion of this molecule represents a carboxylic acid?
Carboxylic acids (-COOH) can react in condensation.
Nuclear Decay Products
Different types of radiation have different penetrative power. As a general trend, the less massive the type of radioactive particle, the greater the penetration. In order of penetration we have: Alpha particles- least penetrative ability Beta particles- intermediate penetrative ability Gamma particles- greatest penetrative ability What this means to your body is that some of the types of radiation are able to penetrate deeper than others. As illustrated, alpha particles are blocked by your skin, while beta particles can penetrate into your tissues, and gamma particles can penetrate all the way into your bones and organs.
Electron Capture
Electron capture is a relatively rare method by which unstable isotopes can become stable. Few isotopes use this method, which involves, like positron emission, a proton becoming a neutron. However, unlike in positron emission where a positron is emitted, in electron capture, as the name suggests, an electron is captured by a proton, resulting in the formation of a neutron. The mechanism for a proton converting into a neutron in electron capture can be explained through charges. As we know, electrons have a -1 charge while protons have a +1 charge. If a proton and electron are combined we see the +1 and -1 charges cancel to form a charge of 0, the charge of a neutron. Also, unlike the other radioactive processes we saw where an unstable isotope is stabilized by emitting, in electron decay, the electron is absorbed. Consider the electron capture of Beryllium-7: B47e+β--10→L37i As we see above, the electron is on the reactant and NOT the product side. As the electron is absorbed, the atomic number decreases from 4 to 3 as a proton becomes a neutron. The new atomic number of 3 shows us that the product is a nucleotide of Li that can be written as Lithium-7. This reaction is also modeled below: Transcript Link As we see above, a proton from the Be absorbs an electron, becoming a neutron in the process. Again, the electron is on the reactant side as illustrated.
Endothermic and Exothermic Reactions
Energy can flow into a system from the surroundings or from the surroundings into the system. The terminology we use for these processes is: Exothermic: Energy from system to surroundings (energy released) Endothermic: Energy from surroundings to system (Energy absorbed) A good mnemonic is that exo = exit (energy exits). An example of an exothermic process is a burning match. The burning match releases heat into the surroundings and is thus classified as exothermic. On the other hand, you may have used a chemical cooling pack to treat an injury. In a chemical cooling pack, the chemical reaction absorbs heat from the surroundings, cooling your injury. Since energy is going from the surroundings to the system, we would consider this process endothermic. What about ice melting? Would you consider this to be endothermic or exothermic? Is energy going in, or is energy going out? Ice melting is endothermic as energy goes into the ice, giving the molecules of water the energy they need to move more quickly. This transforms the solid. As a material absorbs energy (endothermic), the atoms and molecules in the material move more quickly and the state of the material changes from solid to liquid to gas. Opposingly, as a material releases energy (exothermic), the atoms and molecules slow down, moving from gas to liquid to solid.
Energy and First Law of Thermodynamics
Energy takes many forms. A few of the more common forms of energy we observe are light, heat, mechanical energy, and electricity. Energy is the driving force of this universe and necessary for all life, light, and movement. Energy can be measured using various units, including calories and joules. A good starting point in understanding the flow of energy is the First Law of Thermodynamics: Energy in an isolated system cannot be created or destroyed, only transferred. This law is often also known as Conservation of Energy, as this law tells us that energy is conserved and simply moved from one place to another and one form to another. For example, when you drive a car down the road, you are converting the chemical energy found in gasoline into heat and kinetic (movement) energy. None of this energy is destroyed or eliminated in this process. As another example of the first law of thermodynamics in action consider a falling stone hitting the earth. The kinetic energy of this stone is converted mainly into sound, and vibration. In both of these examples, we see that energy can move from one form to another. You may have noticed the term "isolated system" in the 1st Law of Thermodynamics. This term means a system where no matter and no energy goes into or out of the system. Our universe, as we understand it, is an example of such a system, so this law applies to our universe.
Endothermic Reactions: Photosynthesis, Chemical Ice Pack, Iron Melting, Methanol Evaporating.
Exothermic Reactions: Water Freezing, Mixed Chemicals producing Heat, Water Condensing, Burning Gas
These and other imaging technologies allow for healthcare providers to better make medical judgments and improve patient outcomes in a less invasive way. The resolution of these scans has dramatically decreased the need for invasive surgery.
For an individual receiving a medical scan, the benefits generally greatly outweigh the risks. The improved outcomes provided by accurate diagnosis, early detection, and avoiding exploratory surgery more than justify a short exposure to ionizing radiation. Precautions are also put into place to minimize exposure, including shielding of areas not being scanned and short exposure times. Each year, hundreds of thousands of medical scans are completed around the world safely. While an individual undergoing nuclear imaging is exposed to a small dose, those healthcare workers administering the scan take precautions to limit exposure to themselves over the long term. To avoid exposing themselves to the radiation from administering many scans each day, workers use shielding such as lead-lined rooms and track their exposure with radiation badges.
Type of Decay Radiation released Mass of particle Charge of Particle Type of Radiation
Gamma ^0 0γ 0 0 Electromagnetic
Type of Process Effect on mass number Effect on atomic number
Gamma No change No change
Which type of radiation would penetrate most deeply into your body?
Gamma decay produces highly penetrating gamma particles.
Determining How Many Half Lives Have Passed
If the episodes of a show that you would like to watch are each 30 minutes long, how many episodes could you watch in 90 minutes? This was likely a very simple problem to solve by simply considering how many times 30 fits into 90. In other words, you divided the time that you had (90 mins), by the time of an episode (30 mins). This told you how many episodes could fit in that time frame. This is the same way we will use to determine how many half lives have occurred! How much of a radioactive sample that will remain over time depends on both the half life of the material as well as how much time has passed. The more time that passes, the less of your original radioactive sample you have. The first step to completing half life calculations is to determine how much of a material remains after a given period of time. Let us consider a specific situation: If we had a sample of radioactive material with a half life of 30 minutes, how many half lives will have occurred in 90 minutes? To solve this, I would simply divide the time that has passed by the half life, making sure both times had the same unit: Total time/Half life=90 mins/30 mins= 3 half lives As we see above, just like the question on episodes that you solved earlier in this lesson, we simply divided 90 mins by 30 mins to determine how many times 30 could fit into 90. This told us how many half lives could fit in the time frame. As another example, let us say that a material has a half life of 12 hours. How many half lives have happened in two days? To solve this, we would again divide the total time by the half life: Total time/Half life=48 hours/12 hours= 4 half lives Note how we used 48 hours for the total time instead of 2 days. This is because both units of time must match, so we simply converted days into hours.
Half Life Calculations
If we know the number of half lives that have passed, determining how much of a radioactive material remains is as simple as dividing by two as many times as there are half lives. For example, if I have 60 g of a radioactive isotope and 3 half-lives have passed: 1st half life: 60 g/2 =30 g 2nd half life: 30 g/2 = 15 g 3rd half life: 15 g/2 = 7.5 g So after 3 half lives, we have 7.5 grams. Once we know the amount of half lives, calculating how much of a radioactive substance remains is just that easy! One way to set this up is to draw a simple chart. We will use this method to solve the question: What % of an unstable isotope will remain after 4 half lives? Number of half lives/Amount remaining 0 (initial) / 100 % 1 / 50 % 2 / 25 % 3 / 12.5% 4 / 6.25 % You just divide by two 4 times, and get the final answer of 6.25 %. This means that after 4 half lives, 6.25 % of this sample will remain. Now that you know how to calculate the number of half-lives and also know how to determine the amount remaining given the number of half-lives. Let us now put these skills together to determine the answer to questions such as: An isotope of Bismuth-214 has a half life of 20 minutes. How many grams of a 16 gram sample will remain after 60 minutes? First, we determine the number of half lives by dividing the total time by the half life: Total time/Half life=60 mins/20 mins=3 half lives Next, we use the half life to divide the sample amount by two the number of times that we have half-lives. 1st half life: 16 g/2 = 8 g 2nd half life: 8 g/2 = 4 g 3rd half life: 4 g/2 = 2 g Therefore, two grams of Bismuth-214 will remain after 60 minutes. As we saw, the process of calculating half life is a simple, two step process. Step 1: Calculate how many half lives have passed Step 2: Start with initial amount of sample and divide by two that many times
Half Life
In nuclear chemistry, half life is a measure of how much time is required for the radioactivity of a specific radioactive material to decrease to half the original value. As we explored earlier, unstable isotopes decay over time. Some radioactive isotopes decay more quickly than others, and thus a wide range of half life values are possible, from infinitesimal fractions of a second to longer then the current age of the universe. Radioactive isotopes decay using one or more of the radioactive decay types you have studied. These processes occur over time and if we know the half life of a given radioactive material, we can predict how much of that material will still be radioactive after a given period of time. Radioactive Iodine-131, an isotope frequently used in healthcare, has a half life of 8 hours. This results in the radioactivity of Iodine-131 decreasing by half of its current value every 8 hours. As you see, this results in an exponential decrease in the radioactivity of this material over time. Please note the dotted line indicating the trend of this decay. This chart also shows us that after 16 hours, two half-lives have occurred, meaning that this sample only has 25% of the original radioactivity after this period of time.
Which of the following procedures would you expect to expose you to the least amount of radiation?
In terms of radiation risk, nuclear imaging exposes you to less radiation overall as compared to radiation therapy.
The mass number of oxygen does not effect this equation and we divide the total time by the half life as usual.
In this case, 14 / 3.5 = 4.
We must make sure both units of time are the same before dividing.
In this case, 4 hours x 60 minutes/hour = 240 minutes / 30 minutes = 8 half lives.
Which type of radiation would you consider ionizing radiation?
Ionizing radiation can alter the electron structure of an atom, causing an ion to form. Gamma rays are ionizing radiation.
These are sources of radiation we can encounter in our day to day lives.
Ionizing radiation sources include high energy UV lamps, CT scans, the sun, and radon gas. Non-ionizing sources include microwave ovens and cell phones.
The reason we can express this as an He2+ is that this particle has an atomic number of 2 (therefore helium) and, as this particle does not have any electrons, the +2 charge from the protons is not balanced out. One unstable isotope that undergoes alpha decay is Tellurium-104.
Note in the equation below how the total of the top number and the total of the bottom number does not change due to conservation of mass and charge.
Radiation All Around Us
Now that we understand the major classes of radiation, let us look into specific examples in the real world. Radiation appears in many forms, and before moving on, take a moment to identify some forms of radiation that you may be exposed to right now. Once you have recorded the types of radiation you propose you are being exposed to, keep this on hand as we explore real world sources of radiation. Keep in mind, this is not an exhaustive list, but will give us the ability to identify radiation we encounter on a day-to-day basis.
Nuclear power is one of the first areas that often come to mind when considering the uses of radioactive materials. Nuclear energy is a relatively clean source of energy and has the potential to provide sustainable energy in many areas of the world.
Nuclear power has faced defunding after a number of high profile incidents; however, with the volatility of many sources of energy, the next generation of nuclear reactors is being researched. A common misconception with nuclear power plants is that the emissions are of radioactive material; however, the emissions, as seen in the image, are steam from the power generation process. An important consideration of nuclear power generation is what to do with the radioactive waste generated. Current methods involve burial in uninhabited barren areas away from sources of water or volcanic/seismic activity to prevent release into the environment. Other proposed technologies involve reusing nuclear waste for power generation. One interesting biproduct from nuclear power generation is nuclear isotopes that can be used in healthcare.
Which of the following technologies depend on radioactive isotopes to function. Select all that apply.
PET scans and nuclear power generation both require radioactive isotopes to function.
An isotope of phosphorus with a mass number of 32:
Phosphorus-32
Styrene is the monomer for Styrofoam polymer.
Proteins, cotton, rubber, and silk are all polymers.
A nuclide is an isotope that exists long enough to be measured. You likely remember the term Isotope from earlier in the session and this term refers to atoms of a specific element that differ based on their mass number. A few more important terms to remember:
Proton: +1 charged subatomic particle found in the nucleus with a mass of 1 AMU Neutron: uncharged subatomic particle found in the nucleus with a mass of 1 AMU Electron: -1 charged subatomic particle with a very small mass (~0) Mass number (abbreviated as: A): Protons + neutrons Atomic number (abbreviated as Z): Number of protons in an atom. Determines atomic symbol.
Which of the following is a source of carbohydrates?
sugar, fruits, and bread are sources of carbohydrates.
By dividing the time that has passed by the half life, we can determine the number of half-lives that have passed
. In this case 12,000/2,400=5.
In this concept, we will discuss one class of biological polymers called carbohydrates. You might be familiar with this class of biopolymers, as they are fruits, grains, and other sweet additions to your daily diet. After completing this lesson, you will be able to
Describe how the composition, structures, and properties of carbohydrates relate to their functions. List common examples of monosaccharides, disaccharides and polysaccharides.
An isotope with a mass number of 131 and an atomic number of 53
An isotope with a mass number of 131 and an atomic number of 53:Iodine-131
As a rocket takes off, energy in the fuel is converted into kinetic energy, heat, and light.
1st law of thermodynamics
Turning on a computer results in electricity being converted into mechanical work, heat, and light.
1st law of thermodynamics
An ice cube melts on a hot day.
2nd law of thermodynamics
On a hot day, you turn on the oven, causing the room to become even hotter.
2nd law of thermodynamics
Disaccharides and Polysaccharides
A disaccharide forms when the hydroxyl group from one monosaccharide reacts with the hydroxyl group of another monosaccharide in a condensation reaction. One molecule of water is released when this glycosidic bond, an ether, forms. The table sugar that you most likely have in your kitchen, sucrose, C12H22O11, is a disaccharide that is composed of one molecule of glucose and one molecule of fructose. The mnemonic to remember common disaccharides is "Diana wears Small, Medium, and Large." Disaccharides are Sucrose, Maltose, and Lactose Sucrose is made when one molecule of glucose condenses with one molecule of fructose. This is common table sugar. Maltose is made when two molecules of glucose combine. Maltose Lactose is made from one molecule of glucose and one molecule of galactose. This is found in milk, and some people cannot digest this disaccharide in a condition known as "lactose intolerance." A polysaccharide is a polymer of many monosaccharides joined through condensation reactions. Common polysaccharides include amylose, amylopectin, glycogen, and cellulose. These are all polymers of glucose, and used for energy storage as well as cell structures. The mnemonic to remember is "Poly Starts Cello Glyding." Polysaccharides are starch, cellulose, and glycogen. Starch is the storage molecule in plants, and glycogen is the storage molecule in animals. Cellulose is the polymer that gives cell walls their rigid shape and structure.
Select all that apply. Carbohydrates can contain _____ functional groups.
Carbohydrates can contain alcohol, and either ketone or aldehyde groups.
What % of a fresh sample of an unstable isotope with a half-life of 4 days remain after 8 days. Assume you start with 100%.
After determining the number of half lives that have passed, we simply divide our starting amount by two that many times.
Au-180 has a half life of 8 seconds. How much of a 60 gram sample will remain radioactive after 32 seconds?
After determining the number of half-lives that have passed, we simply divide our starting amount by two for each half-life that has passed.
Gamma Decay Gamma decay, the most penetrating and fast moving type of radiation we will be studying, is distinct from the other types of decay we have studied. In addition to being massless, the release of gamma radiation does not cause any form of transmutation and will change neither the atomic number nor the mass number. Instead, gamma decay involves a nucleus entering a lower energy state and releasing gamma radiation in the process. A gamma ray is expressed as: γ00
An important example of an isotope that undergoes gamma decay is an isotope of Technetium: Tc-99m. The m stands for metastable (metastable means that the nucleus is in a relatively high energy state). This isotope is widely used in medical imaging and is vital to the field of healthcare. When the nucleus of Tc-99m stabilizes, a gamma ray is produced as seen in the reaction below: T4399mc→γ00+T4399c As we see above, while the nucleotide stabilized, no transmutation occurred as there was a 0 for both the atomic number and charge of the gamma particle. The gamma ray released is a type of high energy photon. Below, we see a model of the nucleus of Tc-99m rearranging into a stable nucleus and releasing a gamma ray in the process.
Examples of polymers include
All major macromolecules include carbohydrates, proteins, lipids, and nucleic acids are polymers, as are rubber, silk, cotton, and plastics
Type of Process Effect on mass number Effect on atomic number
Alpha Decrease by 4 Decrease by 2
Type of Decay Radiation released Mass of particle Charge of Particle Type of Radiation
Alpha ^4 2 α2+ 4 +2 Particulate
isotope
Atoms of the same element that have different numbers of neutrons
Type of Decay Radiation released Mass of particle Charge of Particle Type of Radiation
Beta (electron) ^0 -1β- ~0 -1 Particulate
An unstable isotope has a half life of 3 days. How many kg of a 820 kg sample will remain after 6 days?
By dividing the time that has passed by the half life, we can determine the number of half-lives that have passed. Then we just need to divide by two that many times starting with the initial amount of sample. In this case, 6 / 3 = 2 half lives. 820kg /2 = 410kg /2 = 205kg.
Rank the following applications of radioactive materials from highest exposure (top) to least exposure (bottom).
By understanding risks, we can make informed choices. Highest exposure is radiation therapy, followed by PET scan, X-ray, and smoke detectors.
How many grams of a 4 grams sample of a radioactive material will remain after two half-lives.
Each half-life decreases the amount currently remaining by 50%, so after two half-lives, 4 grams would be 1 gram.
Which of the following are types of electromagnetic radiation?
Electromagnetic reactions do not have mass, so alpha particles are not electromagnetic.
Type of Process Effect on mass number Effect on atomic number
Electron capture No change Decrease by 1
Which of these processes would not be possible?
Energy cannot be created or destroyed in a chemical reaction.
Sort the following process as exothermic or endothermic:
Energy from system to surroundings is exothermic and energy from surroundings to system in endothermic. Thus, Endothermic reactions are carbon dioxide moving from a solid to a gas and mixing chemicals that become cold. Exothermic reactions are burning wood, digesting food, and condensation.
Click and drag to arrange the following by number of monomers, from smallest number of monomers on the top to largest number on the bottom.
Glucose is a single monomer, maltose is a dimer that contains two monomers, and glycogen contains many monomers.
When a cool penny is placed in a hot car in the summer, the heat flows spontaneously from the __________________ to the ________________ in an illustration of the ________________ Law of thermodynamics.
Heat flowing from the hot car interior into the cool penny is an example of the 2nd Law of Thermodynamics.
Which of these would you classify as an exothermic process?
Heat is released in exothermic reactions , like burning wood, and absorbed in endothermic reactions.
Hydrolysis involves...
Hydrolysis involves water molecules used as a substrate to break apart polymers. The result is the formation of monomers.
Hydrolysis reactions are involved in ____ reactions.
Hydrolysis reactions are catabolic reactions because they break bonds.
In condensation reactions, what small molecule is produced as a by-product?
In condensation reactions, what small molecule is produced as a by-product?
Select the correct letter corresponding to the circled glycosidic bond in the structure.
The glycosidic bond is the ether bond linking the two monomers.
Click the glycosidic bond in the following disaccharide.
The glycosidic bond joins the two monomers, and forms an ether functional group.
Important Note: Mass and charge are conserved in all decay processes.
In other words, the total mass and charge must be the same on both sides of the reaction.
When formed into long chain polymers, they can store energy for future use in the cell such as starch in plants, and glycogen in humans.
In plant cells, carbohydrate polymers called cellulose form rigid protective structures called the cell wall.
Neodymium-161 h as a half life of about 500 ms. What % of a fresh sample of this material would I have after 1 second?
Make sure both units of time are the same before dividing the total time by the half life as usual. Starting at 100 %, we divide by two for each half life. In this case, there are 1000 ms /s, divided by 500ms = 2 half lives, so after two half lives 25% remains.
Lactose is made of the monomers galactose and glucose. Sucrose is made of the monomers fructose and glucose.
Maltose is made of two glucose monomers.
An isotope with an mass number of 53 and 25 protons:
Manganese-53
Determine if the statement is true for hydrolysis or condensation.
Monomers are a product of hydrolysis, which breaks polymers apart. In this process bonds are broken. In condensation, bonds are formed when monomers are used as a substrate to form polymers.
Select all that apply. Monosaccharides include
Monosaccharides include glucose, fructose, and galactose.
Where will you find sucrose?
Sucrose is found in table sugar.
The atomic symbol of an element can be determined from the:
The atomic number gives the number of protons and determines the identity of the atom.
The main component of table sugar is SUCROSE made of one molecule of glucose which forms a six-member ring in nature, and one molecule of FRUCTOSE also known as fruit sugar.
The disaccharide found in milk is LACTOSE, made of the monosaccharide GALACTOSE that is also known as brain sugar and glucose which is the prominent monosaccharide for energy. The disaccharide MALTOSE is made of two molecules of glucose.
Select all the following situations that you would classify as endothermic processes:
The endothermic reactions are hand sanitizer evaporating and ammonium nitrate dissolving and the solution becomes cold.
we see that all of these types of decay release particulate radiation except gamma.
This is because each of the radiation types has some mass, with the exception of gamma decay where a massless photon of gamma radiation is released.
Which monomers are used to form maltose?
Two molecules of glucose are used to form the disaccharide maltose
Carbohydrates contain
alcohols and either a ketone or aldehyde group.
When sodium hydroxide is dissolved in water within a beaker, you observe that the beaker becomes warm. This situation illustrates:
an exothermic reaction 1st Law of Thermodynamics 2nd Law of Thermodynamics
Condensation reactions are involved in
anabolic reactions because they build polymers.
Protons and neutrons
are found in the core of the atom.
Monomers are small molecules used to
build the large polymers.
Carbohydrates are not used for catalysis,
but are used for energy, energy storage, structures like cell walls, and cell recognition like blood types.
Fructose is a monomer,
lactose and sucrose are disaccharides, and cellulose is a polysaccharide.
Click and drag to arrange the following by relative size, from smallest on the top to largest on the bottom.
monomer dimer polymer