| What is the radius of an atom? | Radius of an atom = 1x10^-10m |
| Where is all of the mass in an atom? | All of the mass in an atom is concentrated in its nucleus |
| What effect does distance have on energy levels? | If an energy level is far away from the nucleus will have a higher energy than energy levels closer to the nucleus |
| How can electrons change energy levels through electromagnetic radiation? | When electrons absorb electromagnetic radiation, they go to a higher energy level and when electrons emit electromagnetic radiation, they return to the lower energy level |
| What happens when an atom loses one electron? | When an atom loses one electron the ion now has a 1+ charge |
| What are isotopes? | Isotopes are atoms of the same element that have different numbers of neutrons |
| What do the atomic number and mass number represent? | The mass number represents the total number of neutrons and protons while the atomic number represents the number of protons / electrons |
| What is radioactive decay? | Radioactive decay is when an isotope with an unstable nucleus gives out radiation to become stable |
| When will a nucleus decay? | When a nucleus will decay cannot be predicted because radioactive decay is completely random process |
| What does activity refer to? | Activity refers to the rate at which a source of unstable nuclei decay |
| What is used to measure the activity of a radioactive source? | A Geiger-Muller tube is used to measure the activity of a radioactive source |
| What is the count-rate? | The count rate is the number of decays recorded each second by a detector (such as a Geiger-Muller tube) and count rate is not the same as activity |
| What is the alpha particles nucleus the same as? | An alpha particles nucleus contains two protons and two neutrons, which means an alpha particle is the same as a helium nucleus |
| Where is the beta particle formed? | The beta particle is formed inside the nucleus when one neutron changes into a proton and an electron |
| What are gamma rays? | What are gamma rays?
Gamma rays are electromagnetic waves from the nucleus |
| What is a neutron in terms of radioactivity? | In terms of radioactivity, a neutron is a radioactive source given out by unstable nuclei |
| How far do alpha particles, beta particles and gamma radiation travel? | Alpha particles can travel around 5cm in air before they collide with air particles and stop
Beta particles can travel further than alpha particles, reaching around 15cm in air before stopping
Gamma rays can travels several meters in air before stopping |
| What material can stop alpha particles, beta particles and gamma particles? | Alpha particles can be stopped by a single sheet of paper
Beta paint flew are stopped by a few millermeters of allluninum
And gamma radiation is stopped by several centimetres of lead |
| How strongly ionising are alpha particles, beta particles, and gamma rays? | Alpha particles are strongly ionising, beta particles are quite strongly ionising, and gamma rays are weaking ionising |
| What happens to the atomic number and mass number during alpha, beta and gamma decay? | During alpha decay, the atomic number decreases by 2 and the mad number decreases by 4
While in beta decay, the atomic number decreases by 1, but the mass number does not change
And in gamma decay the atomic and mass number do not change at all |
| What happens when Radium undergoes alpha decay? | When Radium undergoes alpha decay, it’s 88 protons decrease by alpha’s 2 protons, making the element produced by alpha decay: Radon having 86 protons |
| What happens to a proton in beta decay? | In beta decay, a neutron changes to a proton and an electron |
| What is ejected from the nucleus in beta decay? | In beta decay, the electron produced by the neutron is ejected from the nucleus and it is called a beta particle |
| What happens to the atomic and mass number in beta decay? | In beta decay, the atomic number decreases by 1, but the mass number does not change |
| What is the half life of a radioactive isotope? | The half-life of a radioactive isotope is the time taken for the number of nuclei in an isotopes sample to halve |
| What is the half-life in terms of activity? | In terms of activity, the half-life is the time taken for the activity of an isotopes sample to fall to half its initial level |
| If the half-life is 15 days and the initial count rate is 200 counts per second, what would the count rate be after 45 days? | Because 45=3x15, 45 days is three half-lives, so the initial count rate of 200 would be 25 because, 200/2 = 100, 100/2= 50 and 50/2 = 25 counts per second |
| What can ionising radiation increase? | Ionising radiation can increase the risk of cancer |
| How is irradiation used in sterilisation? | Sterilisation uses Irradiation in the form of gamma when sterilisation through heat is not possible. Objects are sterilised through irradiation by first being wrapped in plastic paper to stop bacteria from entering, then the object is placed near a radioactive isotope that emits gamma radiation, and the isotope is inside a lead shield to protect workers from radiation. And when the lead shield is removed gamma radiation irradiates the object, and the gamma radiation kills any present bacteria |
| Why does the object not become radioactive when it undergoes irradiation? | When the object undergoes irradiation, it does not become radioactive because the object only comes in contact with the radiation, not the radioactive isotope itself. |
| What is used when a lead apron is not enough to reduce radiation? | Alpha can be reduced by wearing gloves, while beta and gamma have higher penetrating power and therefore require a lead apron. But when radiation has an even higher penetrating power, such as in nuclear fuel, shielding can be used where lead walls and a lead-glass screen protect people from radiation. |
| What can a radiation monitor do? | A radiation monitor does not stop radiation, but it measures how much radiation is received, so if someone had received too much radiation, they could be stopped from working with radioactive isotopes |
| What is radioactive contamination? | Radioactive contamination is when unwanted radioactive isotopes end up on other materials. Radioactive contamination is hazardous because the radioactive atoms decay and emit ionising radiation. |
| How dangerous are alpha, beta and gamma radiation? | Alpha radiation can be very dangerous because it is strongly ionising but can be easily stopped by dead cells on the skin’s surface. But if alpha emitters are inhaled from contaminated dust or swallowed from contaminated food, they can be extremely dangerous. When swallowed or inhaled the alpha particles cash into living cells and damage their DNA. While Beta particles are less dangerous because they are less ionising but can easily penetrate into the body and damage cells. Because gamma radiation is weekly ionising and therefore less dangerous, it can penetrate into the body but is likely to pass straight through. |
| How have scientists explored the effects of radiation on humans? | Scientists have explored the effects of radiation on humans through peer review where they publish and share studies, allowing findings to be checked. |
| What is the plum pudding model? | The plum pudding model is a model that infers an atom is a ball of positive charge with negative electrons embedded in it. |
| What was the alpha scattering experiment? | The alpha scattering experiment was when scientists took a piece of gold foil because gold can be hammered out into a very thin foil that is only a few atoms thick. Then they fired alpha particles at the gold foil, which have a positive charge. |
| What was the plum pudding model replaced with? | The plum pudding model was replaced with the nuclear model that shows an atom with mainly empty space, in the centre is a tiny positive nucleus containing almost all the mass and around the edge are the negative electrons. But after Niels Bohr discovered energy levels orbit the nucleus at specific areas energy levels in rings became part of the particle model. |
| Who discovered electrons, energy levels and neutrons? | In 1897 Scientist, J.J Thompson discovered atoms contained tiny negative particles, known as electrons and this discovery showed atoms aren't tiny spheres that can't be divided, but rather; atoms have an internal structure. While Niels Bohr allowed for the development of energy levels by theorising electrons orbit the nucleus at specific distances rather than in a general area. And the scientist James Chadwick discovered the nucleus contains neutral particles called neutrons. |
| What conclusions were drawn in response to Rutherford's nuclear model experiments? | Conclusions that were drawn in response to Rutherford's nuclear model experiments include:
because most of the alpha particles went straight through the gold foil atoms are mainly empty space,
because some of the alpha particles were deflected the centre of the atom must have a positive charge,
and because some alpha particles bounced straight back the centre of an atom must contain a great deal of mass. |
