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Radioactivity
GCSE Physics and combined science
| Question | Answer |
|---|---|
| Define atom | The smallest part of an element that can exist. |
| All substances are made up of…? | atoms |
| The radius of an atom is …? | 0.1 nm (1 x 1010 m) |
| The overall charge on an atom is… | zero/neutral |
| Define element | Contains only one type of atom |
| Substances found in the periodic table are…? | elements |
| Approximately how many elements are there? | 100 |
| Define isotope | An atom of the same element with different numbers of neutrons |
| Define radioactive decay | An unstable nucleus changes to become more stabe and gives out radiation |
| We cannot predict when a given atom will decay, this means that radioactive deacy is ….? | random |
| Define activity | Rate at which decay occurs |
| What are the units of activity? | Becquerels (Bq) |
| Define count rate | Number of decays recorded each second by a Geiger-Muller tube |
| Defne half life | The time taken for number of radioactive nuclei in a sample to halve OR time taken for count rate (or activity) from a sample to fall to half its initial value |
| Define contamination | The unwanted presence of materials containing radioactive atoms |
| Define irradiation | When an object is exposed to radiation |
| Does an irradiatied object become radioactive itself? | no |
| The process of radiation removing electrons from atoms to form ions is called…? | ionisation |
| If ionisation happens in DNA it can cause ___________ which may result in ____________ | mutations, cancer |
| Define peer review | Checking of scientific results by other scientific experts |
| Define mass number | The total number of protons and neutrons in an atom |
| Define atomic number | The number of protons in an atom (number of electrons is the same in a neutral atom) |
| Electrons in atoms are located in ___________ | energy levels |
| Absorption of radiation by an atom may result in ____________ moving to a ________________ energy level | electrons, higher |
| Emission of radiation from an atom may lead to _____________ moving to a ______________ energy level | electrons, lower |
| Who came up with the Plumb Pudding model of the atom | J J Thompson |
| Describe the Plum Pudding model of the atom | A ball of positive charge with negative electrons embedded in it |
| Was the Plum Pudding model correct? | no |
| What experiment did Rutherford do? | Alpha particle scattering |
| What did Rutherford's experiment reveal? | Atoms have a central area of positive charge with electrons surrounding it |
| Who discovered that electrons are located in energy levels? | Niels Bohr |
| What did Jame Chadwick discover about the atom? | That the nucleus contains neutrons as well as protons |
| What did John Dalton contribute to our understanding of atomic theory? | Matter is made up of descrete, spherical particles, known as atoms |
| Name the three subatomic particles | proton, neutron, electron |
| Which particles are located in the atoms nucleus | protons, neutrons |
| What is the charge of each subatomic particle? | proton +1, neutron 0, electron -1 |
| What is the mass of each subatomic particle? | proton 1, neutron 1, elecrton ≈ 0 |
| Name the three types of radiation | alpha, beta and gamma |
| What is an alpha particle? | two protons and two neutrons |
| What is a beta particle? | an electron |
| What is gamma radiation? | electromagnetic wave (NOT a particle) |
| What is the range of alpha radiation in air? | short - 5 cm in air |
| What is the range of gamma radiation in air? | unlimited in air |
| What's the range of beta radiation in air? | medium - about 1 m |
| What will absorb (stop) alpha radiation? | paper/skin |
| What will absorb (stop) beta radiation? | about 5 mm aluminium |
| What will absorb (stop) gamma radiation? | several centimetres of lead |
| What is the ionising power of alpha radiation? | very high |
| What is the ionising power of beta radiation? | medium |
| What is the ionising power of gamma radiation? | low |
| What is meant by the ionising power of radiation? | how likely it is to ionise atoms which it comes into contact with |
| How does alpha decay alter the mass number of the parent nucleus? | decreases by 4 |
| How does alpha decay alter the atomic number of the parent nucleus? | decreases by 2 |
| How does beta decay alter the mass number of the parent nucleus? | stays the same |
| How does beta decay alter the atomic number of the parent nucleus? | increases by 1 |
| How does gamma radiation alter the mass and atomic number of the parent nucleus | unchanged (energy is released as the particles in the nucleus reorganise to a lower energy arrangement) |
Created by:
JBearfield
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