P1 atomic structure

• What is the approximate radius of an atom?

  $1 \times 10^{-10} \text{ m}$
• How does the radius of the nucleus compare to the radius of an atom?

  The nucleus is less than 1/1000th the radius
• What particles are found in the nucleus?

  Protons and neutrons
• What charge do protons have?

  Positive charge
• What charge do neutrons have?

  No charge
• What is the overall charge of the nucleus?

  Overall positive charge
• Where are electrons found in an atom?

  In energy levels surrounding the nucleus
• How does the energy of an electron relate to its distance from the nucleus?

  Further electrons have higher energy levels
• What happens to an electron when it absorbs electromagnetic radiation?

  It moves from a lower to a higher energy level
• What occurs when an electron emits electromagnetic radiation?

  It returns to a lower energy level
• What are the key concepts regarding electron arrangement in atoms?

  • Electrons are in energy levels
  • Energy levels further from nucleus have higher energy
  • Electrons can change levels by absorbing or emitting radiation
• How does the absorption and emission of radiation affect electron arrangement?

  It causes electrons to change energy levels
• What is meant by an isotope?

  Atoms of the same element with different neutrons
• What is an ion?

  An atom with a charge due to lost or gained electrons
• What do atoms contain in their central nucleus?

  Protons and neutrons
• What charge do protons have?

  Positive charge
• What charge do neutrons have?

  No charge
• What charge do electrons have?

  Negative charge
• What does the atomic number represent?

  Number of protons in an atom
• Why do atoms have no overall charge?

  Electrons equal the number of protons
• What does the mass number represent?

  Total number of protons and neutrons
• How do you calculate the number of neutrons?

  Mass number minus atomic number
• What are isotopes?

  Atoms with the same protons but different neutrons
• What happens when a sodium atom loses one electron?

  It becomes a sodium ion with a +1 charge
• What is the charge of a sodium ion after losing one electron?

  +1 charge
• What happens if an atom loses two electrons?

  It has a +2 charge
• What are the key concepts related to atomic and mass numbers?

  • Atomic number: number of protons
  • Mass number: total of protons and neutrons
  • Neutrons: calculated by mass number - atomic number
  • Isotopes: same element, different neutrons
  • Ions: charged atoms from losing or gaining electrons
• What experiment is used to work out the nuclear model of atomic structure?

  The alpha scattering experiment
• What did ancient Greeks believe about atoms?

  Atoms are tiny spheres that can't be divided
• Why was the discovery of electrons significant?

  It showed atoms have an internal structure
• What model did scientists propose after discovering electrons?

  The plum pudding model
• What does the plum pudding model suggest about atoms?

  Atoms are a ball of positive charge with electrons
• What material did scientists use for the alpha scattering experiment?

  Gold foil
• Why was gold chosen for the alpha scattering experiment?

  It can be hammered into very thin foil
• What are alpha particles?

  Particles with a positive charge
• What did scientists observe about most alpha particles in the experiment?

  They passed straight through the gold foil
• What did the deflection of some alpha particles indicate?

  The center of the atom has a positive charge
• What does it mean if alpha particles bounce straight back?

  The mass of the atom is concentrated in the nucleus
• What is the central part of an atom called?

  The nucleus
• What happens when an alpha particle collides directly with the nucleus?

  It bounces back in the original direction