Atomic Structure

• Explain why atoms have no overall charge

  There is the same number of protons and electrons.

  The charge of an electron and proton are opposite.
• Most of the mass is concentrated in the nucleus shells. The radius of the nucleus is 10,000 times smaller than the radius of the atom.
• Isotope

  The same number of protons but a different number of neutrons
• Why would we not use alpha radiation as a medical tracer?

  1.Alpha particles are big and heavy, so they can only travel a short distance in the body.

  2. Alpha particles are also highly ionizing, which means they can cause a lot of damage to cells.

  3. Alpha radiation is not easily detected outside the body.
• Explain the effect that half-life has on the choice of medical tracker

  1.A shorter half-life means the tracer will decay quickly, so it won't be effective for long-term tracking.

  2. A longer half-life allows for better imaging over an extended period of time.

  3. Some procedures may require a short half-life for quick imaging, while others may benefit from a longer half-life for prolonged observation.
• Explain the plum pudding model of an atom

  1.The plum pudding model suggests that an atom has negative electrons scattered throughout.

  2. According to this model, the positive charge in the atom is spread out evenly, like a field of positive charge.

  3. The negative electrons are embedded within the positive charge, giving the atom a neutral overall charge.
• The unit for radioactivity is Bq (Becquerels) .
• What is the term count rate?

  Counts per second
• What is the piece of equipment used to determine count rate?

  Gieger - Muller tube
• List 3 safety precautions taken when handling a radioactive source

  • Gloves
  • Breathing apparatus
  • Tongs
  • Shielding + Badges
• Define Irradiated

  Exposed to ionising radiation (alpha, beta + gamma)
• Define Contaminated

  Exposed to unstable radioactive atoms
• 4

  alpha

  2
• 0

  B

  -1
• Type of radiation: Alpha

  Description: Helium nucleus

  Penetration: Stopped by paper or skin

  Range in air: a few cm

  Ionising Power: Strongly

  Includes: 2 protons

  2 Neutrons
• Type of radiation: Beta

  Description: High Speed Electron

  Penetration: Stopped by aluminium

  Range in air: several metres

  Ionising Power: Moderately
• Type of radiation: Gamma

  Description: EM Radiation

  Penetration: Stopped by lead or concrete

  Range in air: at least a km

  Ionising Power: Weakly

  Includes: EM means electromagnetic
• Electrons are arranged in different energy levels around the nucleus. If electromagnetic energy is absorbed, then electrons move away from the nucleus (to a higher energy level). If electromagnetic energy is emitted, then the electrons move closer to the nucleus (to a lower energy level).
• Define Half-life

  The time taken for the number of radioactive atoms to half.
• What is the charge of a proton?

  +1
• What is the charge of a neutron?

  0
• What is the charge of an electron?

  -1
• Where are protons found in the atom?

  The nucleus
• Where are electrons found in the atom?

  The shells
• Where are neutrons found in the atom?

  The nucleus
• What is the relative atomic mass of a proton?

  1
• What is the relative atomic mass of a electron?

  1/1836
• What is the relative atomic mass of a neutron?

  1
• What's the term for the bottom number in an element and what does it represent?

  Atomic number, represents number of protons.
• What's the term for the top number in an element and what does it represent?

  Mass number, represents its total number of protons and neutrons added together
• How do you calculate the number of neutrons in an atom?

  number of neutrons = mass number - atomic number
• J.J. Thomson is credited with the discovery of the electron and proposing the plum pudding model.
• Ernest Rutherford carried out an experiment. What two observations did he notice and what did he conclude form the observations?

  1. Most of the alpha particles passed straight through the gold foil.

  2. Some alpha particles were deflected.

  Rutherford concluded that:

  1. Atoms have a mostly empty space, as most alpha particles passed through.

  2. Atoms have a small, dense, positively charged nucleus, as some alpha particles were deflected back.
• Why is alpha radiation harmful to humans?

  Alpha radiation is harmful because it has high-energy particles that can damage living tissue by ionizing atoms and disrupting DNA. It's important to minimize exposure and take safety precautions.
• Why is beta radiation harmful to humans?

  Beta radiation is harmful because it consists of fast-moving electrons or that can go through the body and damage cells and DNA. It can lead to radiation sickness, genetic mutations, and an increased risk of cancer.
• Why is gamma radiation harmful to humans?

  Gamma radiation is harmful to humans because it consists of high-energy electromagnetic waves. These waves can penetrate deep into the body, causing damage to cells and DNA. Gamma radiation is highly ionizing and can lead to radiation sickness, genetic mutations, and an increased risk of cancer. It's important to minimize exposure to gamma radiation and follow appropriate safety measures when working with radioactive materials.