Karteikarten
Atomic Structure - Physics Topic 4
Karten in diesem Stapel (60)
- 1Who discovered that electrons could be removed from an atom?J.J Thompson
- 2What was J.J Thompson's atomic model known as and why?The plum pudding model, because he though atoms were spheres of positive charge with tiny negative electrons in them, like fruit in a plum pudding
- 3Explain Rutherford's experiment and what the results were.They fired a beam of alpha particles at thin gold foil, expecting it to go straight through or be slightly deflected, but some were deflected more than expected, and a few were deflected back the way they has come.
- 4What did Rutherford's experiment results mean?Most of the mass of an atom must be concentrated in the centre in a tiny nucleus as only a few were deflected back.
The nucleus must have a positive charge as it repelled the positive alpha particles
Most of an atom is empty space as nearly all alpha particles passed through
This was the first nuclear model - 5What did Niels Bohr contribute to the development of the nuclear model?Electrons orbiting the nucleus do so at certain distances called energy levels. His theoretical calculations match experimental data.
- 6Who proved the existence of the neutron, and what did this explain?James Chadwick, and it explained the imbalance between atomic and mass number
- 7What is a charge of a: a. Proton b. Neutron c. Electron ?a. +1
b. 0
c.-1 - 8What does most of an atom consist of?Empty space
- 9If the amount of protons is equal to the amount of electrons, what is the overall charge?None / neutral
- 10What happens if electrons absorb EM radiation?They gain energy, and move to a higher energy level that's further to the nucleus
- 11How does an atom become a positively charged ion?By loosing one or more electrons
- 12What is an isotope of an element?Atoms with the same number of protons (same atomic number) but a different number of neutrons (different mass number) I.e. C-14 is an isotope of carbon
- 13What is radioactive decay?The process in which unstable isotopes decay into other elements by giving off radiation to try to become more stable
- 14How do they try to rebalance their atomic and mass numbers?By releasing neutrons
- 15What is ionising radiation?Radiation that can knock electrons off atoms, causing them to become positive ions
- 16What is ionising power?How easily a radiation source can knock electrons off atoms.
- 17What is an alpha particle?A helium nuclei (two neutrons and two protons)
- 18What is alpha radiation?When an alpha particle is emitted from the nucleus
- 19What has more ionising power: Alpha radiation or beta radiation?Alpha radiation
Alpha radiation is strongly ionising, while beta radiation is only moderately ionising - 20What is a beta particle?A fast moving electron released by the nucleus
- 21What is the mass and charge of a beta particle?Mass - virtually none
Charge - -1 - 22What happens when a beta particle is emitted?For every beta particle emitted, a neutron is turned into a proton
- 23What is a gamma ray?A wave of electromagnetic radiation released by the nucleus
- 24Why are they weakly ionising?Because they tend to pass through rather than collide with atoms
- 25What is the form of a nuclear equation?atom before decay ---> atom after decay + radiation emitted
- 26What two things have to be equal on both sides of a nuclear equation?Atomic number and mass number
- 27In alpha decay, how much is the atomic and mass number reduced by?Atomic - 2
Mass - 4 - 28What happens to the charge of a nucleus during alpha decay?It decreases
- 29What happens to the atomic number during beta decay and why?It increases because a neutron turns into a proton
- 30Why doesn't the mass change?Only an electron is lost and they have virtually no mass, and a proton a neutron have the same mass
- 31Why is there no change in the atomic or mass number when gamma rays are given off?Because gamma rays are a way of getting rid of excess energy, not subatomic particles.
- 32How can radiation be measured?With a Geiger-Muller tube and counter, which records the count rate (number of radiation counts reaching it per second)
- 33What can a radioactive substance's half life be used to find?The substances activity - the rate at which it decays.
- 34What is activity measured in?Becquerels (Bq)
1 Bq is 1 decay per second - 35What is a half life?The time taken for the number of radioactive nuclei in an isotope to half
- 36What does a short half life mean?Activity falls quickly as the nuclei are very unstable and decay rapidly.
- 37Why is a short half life dangerous?A high amount of radiation is emitted, however they quickly become safe
- 38Why is a long half life dangerous?Nearby areas are exposed to radiation for (millions of) years
- 39Name 4 sources of background radiation- Radon gas from the ground
- Cosmic rays
- Food and drink
- Buildings and the ground
- Medical
- Nuclear power and weapons test - 40Where do most cosmic rays come from?The sun
- 41What does radiation dose tell you and what is it measured in?The risk of harm to body tissue due to exposure to radiation. It' measured in Sieverts (Sv), but milisieverts are often used as the background radiation is so small.
- 42What is irradiation?Exposure to radiation
- 43How can you reduce the effects of irradiation?Keep sources in lead lined boxes
Standing behind barriers
Being in a different room and using remote controlled arms - 44What is contamination?Unwanted radioactive atoms get onto or into an object
- 45How can contaminating atoms cause harm if they come into contact with someone?They could decay, releasing radiation
- 46Why is beta and gamma radiation more dangerous than alpha radiation outside the body?Beta particles and gamma rays can penetrate the body and damage organs, while alpha particles can't penetrate the skin
- 47Why is alpha radiation more dangerous than beta or gamma radiation inside the body?Alpha particles are strongly ionising, and damage a very localised area, while beta particles are more spread out and some can pass through the body. Gamma rays are weakly ionising and they mostly pass out of the body
- 48How does radiation cause cancer?Lower doses of radiation causes minor damage, without killing the cells. This means that the number of mutant cells rises as they divide uncontrollably
- 49How does radiation sickness occur?Higher doses kill cells - leading to vomiting, tiredness and hair loss if a lot of cells are killed at once
- 50Why are gamma sources used in medical tracers?They are weakly ionising and pass out of the body
- 51Why is radiation used to treat cancers?High doses of ionising radiation kill living cells
- 52What is nuclear fission?A type of nuclear reaction used to release energy from large, unstable atoms by splitting them into smaller atoms
- 53How is nuclear fission a chain reaction?When an atom splits, two or three neutrons are released. If they are moving slow enough, they could be absorbed into another atom, causing more fission as the atom splits into two similarly sized elements
- 54What happens to the energy produced in nuclear fission that isn't transferred into the kinetic energy stores?It's carried away by gamma rays
- 55How is nuclear fission used to create electricity?The energy carried by gamma rays and in the kinetic energy stores can be used to heat water, making steam to turn turbines and generators.
- 56How is nuclear fission controlled?Control rods are lowered and raised inside a reactor and absorb neutrons, slow down the chain reaction and control the amount of energy being released
- 57What happens if nuclear fission isn't controlled?Lots of energy is released, resulting in an explosion - so that's how nuclear weapons work.
- 58What happens during nuclear fusion?Two light nuclei collide at high speed at high speed and join (fuse) to create a heavier nucleus
- 59Why does the heavier nucleus not have as much mass as the two lighter ones?Some mass is converted into energy and then released as radiation.
- 60What releases more energy: nuclear fusion or fission?Nuclear fusion
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- Year 10 Physics (Phys 4 - Atomic Structure) Karteikarten am Atomic Structure - Physics Topic 4, erstellt von Jessie Howes am 25/06/2017.
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- Jessie Howes
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