atomic structure , isotops , electron shells

• What is the central part of an atom called?

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

  Protons and neutrons
• What is the charge of neutrons?

  Neutral
• What is the charge of protons?

  Positive
• 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 electrons?

  Negative
• 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 represent?

  The number of protons in an atom
• Why is the atomic number important?

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

  7
• How is the mass number calculated?

  By adding the number of protons and neutrons
• How many protons does lithium have?

  3
• How many electrons does lithium have?

  3
• What are isotopes?

  Atoms with the same number of protons but different numbers of neutrons
• What is an example of an isotope of lithium?

  Lithium-6
• What happens to unstable isotopes?

  They tend to decay into other elements by emitting radiation
• What is the process called when unstable isotopes decay?

  Radioactive decay
• What are the types of radiation emitted during radioactive decay?

  Alpha, beta, or gamma radiation
• What happens when an electron gains enough energy?

  It can jump to a higher energy level
• How are electrons arranged in an atom?

  In energy levels called shells
• What is an excited electron?

  An electron that has jumped to a higher energy level
• What provides the energy for an electron to jump energy levels?

  Electromagnetic radiation
• What happens after an electron becomes excited?

  It falls back down to a lower energy level and re-emits energy
• What is ionization?

  When an outermost electron absorbs enough energy to leave the atom
• What is a positive ion?

  An atom with more protons than electrons
• What does ionizing radiation do?

  It can knock electrons off atoms
• What are the key components of an atom?

  • Nucleus: contains protons and neutrons
  • Protons: positively charged, mass of one
  • Neutrons: neutral, mass of one
  • Electrons: negatively charged, much smaller than protons/neutrons
• What information is found in a periodic table box?

  • Elemental symbol (e.g., Li for lithium)
  • Atomic number (number of protons)
  • Mass number (total number of protons and neutrons)
• What is the relationship between protons and electrons in an atom?

  • The number of protons equals the number of electrons in a neutral atom.
• What are the characteristics of isotopes?

  • Same number of protons (same atomic number)
  • Different number of neutrons (different mass numbers)
  • Generally, only one or two isotopes are stable
• What happens during radioactive decay?

  • Unstable isotopes emit radiation (alpha, beta, gamma)
  • They decay into other elements
• How do electrons behave in energy levels?

  • Arranged in shells around the nucleus
  • Can jump to higher energy levels when gaining energy
  • Fall back and re-emit energy as radiation
• What is the significance of ionization in atoms?

  • An outermost electron can leave the atom if it absorbs enough energy
  • Results in a positive ion (more protons than electrons)