Unit 2 - atomic structure Flash Cards

Play Memory | Create Card File | Append to Card File
Title: Unit 2 - atomic structure
Description: GCSE revision
Number of Cards: 48
Save Count: 2
Author: Cyberphysics
Created: 2009-12-31
Tags: 2 cyberphysics gcse physics unit
Private No

Save Count represents the number of people who have saved this card set to their flashcard list. Consider this an endorsement!

    • Question
    • Answer
    • Side 3
    • Who devised the experiment that changed the way we thought of the atom in 1911?
    • Ernest Rutherford
    • Who carried out the experiment that changed the way we thought of the atom in 1911?
    • Geiger and Marsden – two research students working for Rutherford.
    • What was the outcome of the Rutherford (Geiger and Marsden) scattering experiment?
    • A change in the scientific thinking of what the atom's structure is like.
    • What was the target in the Rutherford (Geiger and Marsden) experiment?
    • Very thin gold foil (so it was only a couple of atoms thick).
    • What was fired at the gold foil in the Rutherford (Geiger and Marsden) experiment?
    • Alpha particles
    • Why was the gold foil fired at in a vacuum in the Rutherford (Geiger and Marsden) experiment?
    • Air would have absorbed the alpha particles before they reached the gold foil
    • How was the path of the alpha particles detected in the Rutherford and Marsden experiment?
    • When the alpha particles hit a zinc sulphide screen a flash of light was seen.
    • What was the model of the atom that preceded the nuclear model?
    • The ‘plum pudding’ model of the atom.
    • What were the findings of the Rutherford Geiger and Marsden) experiment
    • Most of the alpha particles went straight through the gold foil or were deflected a tiny bit (as expected) but about 1 in 8000 were backscattered – deflected by more than 90 degrees
    • What was concluded from the Rutherford and (Geiger and Marsden) experiment?
    • That the atom had a dense, small, positively charged nucleus orbited by electrons so it is neutral overall and most of the atom is empty space
    • What was the 'plum pudding' model like?
    • A sphere of positive charge with negative charges embedded in it - like currants in a Christmas plum pudding.
    • What is the nuclear model of the atom like?
    • A tiny, dense, positive nucleus with negative electrons orbiting it (like the planets orbiting the Sun)
    • What is the mass of a proton (in atomic mass units)?
    • 1u
    • What is the mass of a neutron (in atomic mass units)?
    • 1u
    • What is the mass of an electron (in atomic mass units)?
    • Negligible to that of the proton or neutron - 0.00055u - NEVER say it is zero!
    • What is the charge of a proton?
      (in relative atomic charge units NOT coulombs)
    • +1 (no unit is necessary here)
    • What is the charge of a neutron?
      (in relative atomic charge units NOT coulombs)
    • zero
    • What is the charge of an electron?
      (in relative atomic charge units NOT coulombs)
    • -1 (no unit is necessary here)
    • What is the charge on an atom if the number of electrons is equal to the number of protons in the nucleus?
    • The atom has no net electrical charge.
    • What is an atom called that loses or gains electrons?
    • An ion.
    • What is significant about the number of protons in the nucleus?
    • All atoms of a particular element have the same number of protons.
    • What is an isotope?
    • Atoms of the same element (therefore having the same number of protons as each other) which have different numbers of neutrons are called isotopes.
    • What is atomic number?
    • The total number of protons in an atom's nucleus is called its atomic number.
    • What is the mass number?
    • The total number of protons and neutrons in an atom's nucleus is called its mass number.
    • What is an alpha particle?
    • Two protons and two neutrons (a helium nucleus) that comes out of a nucleus.
    • What is a beta particle?
    • A fast electron that comes out of the nucleus.
    • What is a gamma ray?
    • High energy electromagnetic radiation.
    • Does losing a gamma ray change the particles in the nucleus?
    • No, it is still the same nucleus - it is just at a lower energy level.
    • What happens when a nucleus loses an alpha particle?
    • The nucleus loses two protons (therefore becoming a nucleus of a different element) and two neutrons.
    • What happens when a nucleus loses a beta particle?
    • The nucleus loses a neutron and gains a proton (therefore becoming a nucleus of a different element). The neutron has emitted a beta particle (losing negative charge and becoming positive).
    • Where does artificial background radiation come from?
    • Nuclear weapons and testing and nuclear power plants - medical uses.
    • Where does natural background radiation come from?
    • Cosmic rays, natural radioactive isotopes in the rocks and atmosphere - from there in food etc too - mainly (50%) radon in the atmosphere.
    • What is nuclear fission?
    • The splitting of atomic nuclei (speak of the nucleus splitting not the atom!)
    • How many parts does the nucleus split into?
    • Two
    • What else is produced besides the two fission fragments?
    • Besides the two smaller nuclei 2 or 3 neutrons are also released.
    • What is nuclear fission used for?
    • It is used in nuclear reactors as a source of heat energy which can be transformed to electrical energy.
    • What is nuclear fusion?
    • It is the joining together of two small atomic nuclei into one big nucleus. (Talk of nuclei not atoms!).
    • What is nuclear fusion used for?
    • It is the process by which energy is released in stars. We are trying to create fusion reactors but haven't done it yet.
    • Name the two fissionable substances in common use in nuclear reactors.
    • Uranium 235 and Plutonium 239.
    • What is induced fission?
    • When we start the fission process off (like induced births...)
    • What type of fission occurs with uranium 235 or plutonium 239?
    • Induced fission - the nucleus must first absorb a neutron to start the process off.
    • Why does a chain reaction occur?
    • The neutrons released may go on to cause another fission which in turn releases more neutrons that then cause more fissions and so on. This is called a chain reaction.
    • What is the process by which energy is released in stars?
    • Nuclear fusion.
    • Which process (fusion or fission) releases the most energy per kilogram?
    • Fusion
    • What slows neutrons down?
    • Graphite moderator (moderates the speed of neutrons so they are more likely to be absorbed by the uranium nucleus)
    • What absorbs neutrons?
    • Boron control rods
    • What is nuclear fuel?
    • Pellets of enriched uranium or plutonium are put into fuel rods.
    • Why is thick concrete shielding necessary around a nuclear reactor?
    • Radioactive isotopes give out alpha, beta and gamma rays - gamma rays are very penetrating so a thick dense barrier needs to be put around it.