Atomic structure

• What are the three main sub-atomic particles found within an atom?

  Protons, electrons, and neutrons
• How do sub-atomic particles influence an atom?


  They influence the physical and chemical properties of the atom
• Where is the nucleus located in an atom?

  The nucleus is at the center of the atom
• What is the composition of the nucleus?


  The nucleus contains protons and neutrons
• What is the charge of a proton?


  +1
• Where are electrons found in an atom?

  Electrons orbit the nucleus
• What is the charge of an neutron?

  0
• What is the mass of an electron in Atomic Mass Units?

  Approximately 1/1836
• What is the mass of a neutron in Atomic Mass Units (A.M.U.)?

  1 A.M.U.
• What is the charge of a neutron?


  0
• Why are atoms and sub-atomic particles weighed in Atomic Mass Units (A.M.U.)?


  Because they are too small to be weighed in grams
• Electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.
• What is used to identify an atom?

  The number of protons
• What is the atomic number?

  The number of protons in the nucleus of an atom
• How does the atomic number relate to electrons in an atom?

  The atomic number is the same as the number of electrons in a neutral atom
• What does the mass number indicate?

  The number of protons and neutrons in the nucleus of an atom
• How would you calculate the mass number?

  Mass number = number of protons + number of neutrons
• What is the relationship between protons, electrons, and neutrons in an atom?

  Protons and electrons are equal in number, while neutrons can vary
• What is the approximate radius of an atom?

  About 0.1 nm (1x10^-10 m)
• How small is the nucleus compared to the atom?

  The nucleus is less than 1/10,000 of the size of the atom
• What are isotopes?

  Isotopes are atoms with the same number of protons but different numbers of neutrons
• Why does chlorine have a mass number of 35.5 in the periodic table?

  Because it has two isotopes with different mass numbers
• How many isotopes does chlorine have?

  Chlorine has two isotopes
• What is the ratio of 37Cl to 35Cl atoms?

  For every 1 atom of 37Cl, there are 3 atoms of 35Cl
• How is the weighted average mass of a chlorine atom calculated?

  By using the formula: \((x_{37} \times 37) + (x_{35} \times 35) = 35.5\)
• What is the electronic structure of an atom?

  • Electrons are found in shells around the nucleus
  • The first shell holds up to 2 electrons
  • The second shell holds up to 8 electrons
  • The third shell holds up to 8 electrons
  • The arrangement of electrons is called electronic configuration
• How many electrons can the first shell hold?

  Up to 2 electrons
• How many electrons can the second shell hold?

  Up to 8 electrons
• How many electrons can the third shell hold?

  Up to 8 electrons
• What is the electronic configuration for the following elements?


  • Hydrogen: (1)
  • Lithium: (2, 1)
  • Magnesium: (2, 8, 2)
  • Potassium: (2, 8, 8, 1)
  • Neon: (2, 8)
• What is the electronic configuration of magnesium?

  (2, 8, 2)
• What is the electronic configuration of potassium?

  (2, 8, 8, 1)
• What is the electronic configuration of neon?

  (2, 8)
• What is the electronic configuration of lithium?

  (2, 1)
• What is the electronic configuration of hydrogen?

  (1)