Foundations

• What does atom consist of?

  • nucleus made up of two types of subatomic particles such as protons & neutrons
  • third type called electron, outside nucleus. Arranged around nucleus in shells
• What charge does Proton have?

  +1
• What charge does Neutron have?

  0 charge
• What charge does Electron have?

  -1 which is same as proton
• Nearly all of atoms mass is in the nucleus
• What’s Protons relative mass?

  1
• What’s Neutrons relative mass?

  1
• What’s Electrons relative mass?

  1/1836
• As the nucleus gets larger more neutrons are needed
• Total positive charge from protons is cancelled by the total negative charge from electrons
• What’s atomic number?

  Number of protons
• Different elements contain different number of protons
• What are Isotopes?

  Atoms of the same element with different numbers of neutrons and different masses
• What’s Mass number? The total number of protons and neutrons in the nucleus of an atom
• Different isotopes of an element react in same way but have different properties
• The number of neutrons has no effect on reactions of an element
• What is the definition of relative atomic mass (Ar)?

  The average mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12.
• Why is carbon-12 used as the standard for relative atomic mass?

  Because it has a relative atomic mass of 12, providing a consistent reference point.
• What is the relative atomic mass of carbon?

  12
• How does the relative atomic mass of an element relate to carbon-12?

  It is compared to one twelfth of the mass of an atom of carbon-12.
• What is the relative isotopic mass?

  The mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12
• What is the relative formula mass used for?

  It is used for giant covalent compounds or ionic compounds
• What does relative atomic mass represent?

  The weighted mean mass of an atom of an element relative to 1/12 of the mass of an atom of carbon-12
• What factors are considered in calculating the weighted mean mass of an element?

  The percentage abundance of each isotope and the relative isotopic mass of each isotope
• In the periodic table, what additional information is shown alongside the atomic number for each element?

  Relative atomic mass
• What is relative isotopic mass?

  • The mass of an isotope relative to 1/12 of the mass of an atom of carbon-12
  • It has no units because it is a ratio of two masses
• Why does relative isotopic mass have no units?

  Because it is a ratio of two masses
• How does relative atomic mass differ from relative isotopic mass?

  Relative atomic mass is the weighted mean of all isotopes, while relative isotopic mass is specific to a single isotope