Structure of the Atom

• What do atoms consist of?

  Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells.
• How can the number of subatomic particles in an atom be calculated?

  The number of subatomic particles can be calculated from the atom's atomic number and mass number.
• What is the structure of the atom?

  • Central nucleus containing protons and neutrons
  • Surrounded by electrons arranged in shells
  • Nucleus contains most of the atom's mass
• What is the radius of an atom approximately?

  The radius of an atom is about $0.1 \text{ nm} (1 \times 10^{-10} \text{ m})$.
• How does the radius of a nucleus compare to that of an atom?

  The radius of a nucleus is less than $\frac{1}{10,000}$ of the radius of an atom.
• What is the radius of a typical bacterium?

  The radius of a typical bacterium is about $1 \times 10^{-6} \text{ m}$.
• What is the radius of a human hair?

  The radius of a human hair is about $1 \times 10^{-4} \text{ m}$.
• What are subatomic particles found in the nucleus of atoms?

  The nuclei of all atoms contain subatomic particles called protons and neutrons.
• What is the charge and relative mass of a proton?

  A proton has a positive charge and a relative mass of 1.
• What is the charge and relative mass of a neutron?

  A neutron has no charge and a relative mass of 1.
• What is the charge and relative mass of an electron?

  An electron has a negative charge and a very small relative mass.
• Where is most of the mass of an atom concentrated?

  Most of the mass of an atom is concentrated in its nucleus.
• What is the relationship between the charges of protons and electrons?

  Protons and electrons have electrical charges that are equal and opposite.
• What is a key fact to remember about protons and neutrons?

  Protons are positive, and neutrons are neutral.
• What are the relative masses and charges of subatomic particles?

  • Proton: Relative mass 1, Charge +1
  • Neutron: Relative mass 1, Charge 0
  • Electron: Relative mass very small, Charge -1
• What are the components of atomic structure?

  • Nucleus: Contains protons and neutrons
  • Electrons: Surround the nucleus in shells
  • Atomic number: Number of protons
  • Mass number: Total number of protons and neutrons
• What is the significance of relative mass in subatomic particles?

  • Relative mass compares the mass of particles
  • Proton: Relative mass of 1
  • Neutron: Relative mass of 1
  • Electron: Very small relative mass