Atomic structures,isotopes,electron shells

• What is the central part of an atom called?

  Nucleus
• What particles are found in the nucleus of an atom?

  Protons and neutrons
• What charge do protons have?

  Positive charge
• What is the relative mass of protons and neutrons?

  One
• How much smaller are electrons compared to protons or neutrons?

  About two thousand times smaller
• What is the charge of an electron?

  Negative charge
• What does each box in the periodic table represent?

  A particular element
• What is the elemental symbol for lithium?

  Li
• What does the atomic number indicate?

  Number of protons in an atom
• Why is the atomic number important for identifying an element?

  It determines which element it is
• What is the mass number of lithium?

  Seven
• How is the mass number calculated?

  Total number of protons and neutrons
• How many protons does lithium have?

  Three
• How many electrons does lithium have?

  Three
• What are isotopes?

  Atoms with the same protons, different neutrons
• What happens to unstable isotopes?

  They decay into other elements
• What is radioactive decay?

  Process of unstable isotopes emitting radiation
• What types of radiation can unstable isotopes emit?

  Alpha, beta, or gamma radiation
• How are electrons arranged in an atom?

  In energy levels called shells
• What happens when an electron gains enough energy?

  It can jump to a higher energy level
• What is meant by an excited electron?

  An electron that has gained energy
• What provides the energy for an electron to jump levels?

  Electromagnetic radiation
• What happens when an electron falls back to a lower energy level?

  It re-emits energy as radiation
• What is ionization?

  When an electron leaves the atom
• What charge does an atom have after losing an electron?

  Positive charge
• What does ionizing radiation do?

  Knocks electrons off atoms
• What are the key components of an atom?

  • Nucleus (protons and neutrons)
  • Electrons in shells
  • Atomic number (number of protons)
  • Mass number (total protons and neutrons)
• What is the process of electron excitation and return?

  1. Electron gains energy from radiation
  2. Jumps to a higher energy level (excited state)
  3. Falls back to lower energy level
  4. Re-emits energy as electromagnetic radiation
• What are the characteristics of isotopes?

  • Same atomic number (protons)
  • Different mass numbers (neutrons)
  • Stable and unstable isotopes
  • Radioactive decay of unstable isotopes