Atomic Structure

• What is the smallest piece of an element that can exist?

  An atom
• What is a substance with only one sort of atom called?

  An element
• What is formed when atoms join together by chemical bonds?

  A molecule
• What is the relative mass of a proton?

  1
• What is the relative charge of a neutron?

  0
• Where are electrons located in an atom?

  In shells around the nucleus
• What does the atomic number represent?

  Number of protons
• What does the mass number represent?

  Number of protons + neutrons
• What are isotopes?

  Atoms of the same element with different numbers of neutrons
• Why is the relative atomic mass an average value?

  It takes into account the abundance of isotopes
• Calculate the relative atomic mass of chlorine given 75% chlorine-35 and 25% chlorine-37.

  35.5
• What is the relative atomic mass of an element if isotope-A has a mass of 10 and is 60% abundant, and isotope-B has a mass of 11 and is 40% abundant?

  10.4
• How does the presence of isotopes affect the relative atomic mass of an element?

  It causes the relative atomic mass to be an average value
• What are the positions, relative masses, and relative charges of sub-atomic particles?

  • Proton: in nucleus, mass 1, charge +1
  • Neutron: in nucleus, mass 1, charge 0
  • Electron: in shells around nucleus, mass 1/1836, charge -1
• What are the key terms related to atomic structure?

  • Atomic number: number of protons
  • Mass number: number of protons + neutrons
  • Isotopes: atoms of the same element with different numbers of neutrons
  • Relative atomic mass: average mass considering isotope abundance
• How do you calculate the relative atomic mass of an element from isotopic abundances?

  R.A.M. = (mass of isotope-A x % of isotope-A) + (mass of isotope-B x % of isotope-B) / 100
• What is the smallest piece of an element that can exist?

  An atom
• What is a substance with only one sort of atom called?

  An element
• What is formed when atoms join together by chemical bonds?

  A molecule
• What is the relative mass of a proton?

  1
• What is the relative charge of a neutron?

  0
• Where are electrons located in an atom?

  In shells around the nucleus
• What does the atomic number represent?

  Number of protons
• What is the mass number of an atom?

  Number of protons + neutrons
• What are isotopes?

  Atoms of the same element with different numbers of neutrons
• Why is the relative atomic mass of an element an average value?

  It takes into account the abundance of isotopes
• Calculate the relative atomic mass of chlorine given 75% chlorine-35 and 25% chlorine-37.

  35.5
• What is the relative atomic mass (R.A.M.) of an element if isotope-A has a mass of 10 and is 60% abundant, and isotope-B has a mass of 11 and is 40% abundant?

  10.4
• Why do atoms have no overall charge?

  Number of protons equals number of electrons
• What is the relative mass of an electron?

  1/1836
• What is the relative charge of a proton?

  +1
• Where are protons located in an atom?

  In the nucleus
• What is the relative charge of an electron?

  -1
• How is the relative atomic mass (R.A.M.) calculated from isotopic abundances?

  (mass of isotope-A x % of isotope-A) + (mass of isotope-B x % of isotope-B) / 100
• If an element has two isotopes, one with a mass of 20 and 70% abundance, and another with a mass of 22 and 30% abundance, what is the relative atomic mass?

  20.6
• Why do isotopes of the same element have different mass numbers?

  They have different numbers of neutrons
• What is the relative mass of a neutron?

  1
• Where are neutrons located in an atom?

  In the nucleus
• What does the mass number represent in an atom?

  Total number of protons and neutrons
• If an element has two isotopes, one with a mass of 14 and 90% abundance, and another with a mass of 15 and 10% abundance, what is the relative atomic mass?

  14.1