science atomic structure

• How small are atoms, and what is their basic structure?

  • Atoms have a radius of about 1 × 10^-10 metres. An atom consists of a positively charged nucleus (containing protons and neutrons) surrounded by negatively charged electrons.
• What is the radius of a nucleus compared to an atom?


  The nucleus is incredibly small, with a radius that is less than 1/10,000 of the atom’s radius. Almost all of the atom's mass is concentrated in the nucleus.
• How are electrons arranged in an atom, and how can their arrangements change?


  Electrons are arranged at different distances from the nucleus, known as energy levels. When an electron absorbs electromagnetic radiation, it moves to a higher energy level (further from the nucleus).

  • When it emits electromagnetic radiation, it moves to a lower energy level (closer to the nucleus).
• What is the relationship between protons and electrons in an atom?


  In an atom, the number of electrons equals the number of protons, making the atom electrically neutral.
• What is the atomic number and mass number?


  The atomic number is the number of protons in an atom.

  • The mass number is the total number of protons and neutrons in the nucleus.
• What are isotopes?

  • Isotopes are atoms of the same element that have different numbers of neutrons, which changes their mass number but not their atomic number.
• How do atoms become positive ions?


  Atoms turn into positive ions by losing one or more outer electrons.
• What was the model of the atom before the discovery of the electron?

  Before the discovery of the electron, atoms were thought to be indivisible tiny spheres. Later, the plum pudding model suggested that atoms are balls of positive charge with negative electrons embedded in them.
• What did the alpha particle scattering experiment reveal?

  The experiment showed that most of an atom’s mass is concentrated in a small, dense, positively charged nucleus. This led to the development of the nuclear model of the atom.
• What was Niels Bohr’s contribution to the atomic model?

  • Niels Bohr proposed that electrons orbit the nucleus at specific distances or energy levels, aligning with experimental observations.
• What did James Chadwick’s experiments discover?

  • Chadwick’s experiments provided evidence for the existence of neutrons in the nucleus, which do not carry an electrical charge.
• What is radioactive decay?


  Radioactive decay is a random process where an unstable nucleus emits radiation to become more stable. This process releases alpha, beta, or gamma radiation, or neutrons.
• What is the definition of activity, and how is it measured?

  • Activity is the rate at which a radioactive substance decays.
  • It is measured in becquerels (Bq), where 1 Bq = 1 disintegration per second.
  • Formula: Activity (Bq) = number of distintergations/time taken (seconds)
• What is an alpha particle, and how does it affect the nucleus?

  • An alpha particle consists of 2 protons and 2 neutrons (equivalent to a helium nucleus).
  • Alpha decay causes the mass and charge of the nucleus to decrease.
• What is a beta particle, and how does it affect the nucleus?

  • A beta particle is a high-speed electron ejected from the nucleus as a neutron turns into a proton.
  • Beta decay increases the charge of the nucleus but does not change its mass.
• What is gamma radiation, and how does it affect the nucleus?

  • Gamma radiation is high-energy electromagnetic radiation emitted from the nucleus.
  • It does not change the mass or charge of the nucleus.
• What is the half-life of a radioactive isotope?

  • Half-life is the time it takes for the number of nuclei in a radioactive sample to halve or for the activity (or count rate) to halve.
• What is radioactive contamination?

  Radioactive contamination occurs when radioactive materials are unintentionally deposited on surfaces or objects.The hazard depends on the type of radiation emitted by the contaminating atoms.
• What is irradiation?

  Irradiation is the process of exposing an object to nuclear radiation.

  • The irradiated object does not become radioactive unless the nucleus is unstable.
• How can alpha radiation be shielded against?

  • Alpha radiation can be blocked by a sheet of paper or protective gloves, as it does not penetrate far.
• How can beta radiation be shielded against?


  Beta radiation can be blocked by materials like plastic or lead aprons.
• How can gamma radiation be shielded against?

  • Gamma radiation requires thick lead or concrete for effective shielding, especially at high doses.
• What forces act within the nucleus, and how do they affect stability?

  • Electrostatic repulsion between protons pushes them apart, while the strong nuclear force binds protons and neutrons together.
  • If the nuclear force is weaker than electrostatic repulsion, the nucleus becomes unstable and will decay.
• half-life= t 1/2

  in caluclator in(2)
• dangers of having equipment contaimated with a atom that had half life of 6 or 8 hours


  Radiation Exposure,Contamination Risk,Decontamination Challenges,Health Risks,Regulatory and Safety Compliance
• why do we use gamma rays in x rays


  Similar Properties,Medical Applications,Source of Radiation,Advantages of Gamma Rays, Safety Considerations
• What was a consequence of using radium paint in factories?

  Environmental contamination
• How did waste materials from radium paint affect the ecosystem?


  They contributed to pollution in the surrounding area
• What are the long-term effects of radium exposure on the environment?

  Radium can leach into soil and groundwater
• Why is the regulation and cleanup of hazardous waste important, as highlighted by the Radium Girls' exposure?


  To prevent similar environmental contamination in the future
• radium girls

  • Contamination from waste materials
  • Long-term effects on soil and groundwater
  • Need for regulations on hazardous waste disposal
  • Importance of environmental cleanup
• What were the wages of the Radium Girls for their work?


  Relatively low wages
• What does the low wages of the Radium Girls raise questions about?


  Fair labor practices and economic exploitation
• How did the factories benefit from the Radium Girls' labor?


  The factories profited while failing to provide safe working conditions
• What were the long-term health consequences for the Radium Girls?


  Significant medical expenses and loss of income
• What economic concerns arise from the neglect of worker safety for the Radium Girls?


  The financial burden placed on affected individuals and families
• What legal actions did the Radium Girls take against their employers?


  They sought compensation for their suffering
• What did the legal battles of the Radium Girls highlight?


  The economic implications of workplace safety and liability
• What changes resulted from the legal actions taken by the Radium Girls?


  Changes in how industries handle hazardous materials
• What ethical issue was raised regarding the Radium Girls and informed consent?


  The Radium Girls were not informed about the dangers of radium exposure.