1.1.3 Atomic Number and Mass Number

• What is the atomic number defined as?

  Number of protons
• Protons and neutrons each have a mass of about 1 atomic mass unit.

  True
• The mass number determines the element's identity.

  False
• What is the definition of the mass number (A)?

  Total protons + neutrons
• Isotopes have the same number of protons but different numbers of neutrons.


  True
• What does the atomic number represent in an atom's nucleus?

  Number of protons
• Why is understanding the mass number important?

  Identifying isotopes
• What changes the mass number of an atom?

  Change in neutrons
• What changes the atomic number of an atom?

  Change in protons
• The mass number of an atom includes the total number of protons and neutrons.


  True
• The mass number is related to both protons and neutrons.


  True
• How many neutrons are in Sodium (Na) with a mass number of 23 and an atomic number of 11?

  12
• How many neutrons are in a Carbon 13 atom?

  7
• How is the number of neutrons calculated in an atom?

  Mass number - Atomic number
• Match the atomic concept with its definition:

  Atomic Number (Z) ↔️ Number of protons

  Mass Number (A) ↔️ Total protons + neutrons
• What is the atomic number of carbon?

  6
• The atomic number of an element determines its chemical identity.


  True
• The atomic number identifies the element in the periodic table.


  True
• What does the bottom number in an atomic symbol represent?

  Atomic number
• Carbon-12 has 6 protons and 6 neutrons.

  True
• How many protons are in a Carbon 12 atom?

  6
• What does the mass number, denoted by A, represent in an atom?

  Total protons and neutrons
• What is the mass number of sodium (Na)?

  23
• What is the atomic symbol for sodium (Na)?


  Na
• The mass number determines the atom's mass.


  True
• What is the relationship between the mass number, atomic symbol, and proton/atomic number of an element?

  • Mass number is the total number of protons and neutrons in the nucleus
  • Atomic symbol is the one or two letter abbreviation for the element
  • Proton/atomic number is the number of protons in the nucleus
• What is the proton/atomic number of sodium (Na)?

  11
• What are the key differences between Carbon 12, Carbon 13, and Carbon 14 atoms?

  • Carbon 12 has 6 protons and 6 neutrons
  • Carbon 13 has 6 protons and 7 neutrons
  • Carbon 14 has 6 protons and 8 neutrons
• What is the relationship between the mass number, atomic symbol, and proton/atomic number of an element?

  Mass number is the total number of protons and neutrons, atomic symbol is the one or two letter abbreviation, and proton/atomic number is the number of protons
• How many neutrons are in a Carbon 14 atom?

  8
• The number of protons in an atom is equal to its atomic number.


  True
• The mass number of sodium is represented by the top number in its atomic symbol.

  True
• What is the proton/atomic number of sodium (Na)?

  11
• What two numbers are used to calculate the number of protons, neutrons, and electrons in an atom?

  Atomic number and mass number
• What is the atomic symbol for sodium (Na)?


  Na
• What is the mass number of sodium (Na)?

  23
• What is the mass number of sodium (Na)?

  23
• What is the atomic number of sodium (Na)?

  11
• In a neutral atom, the number of electrons is always the same as the number of protons.


  True
• If carbon-12 is 99% abundant, what is its contribution to the average atomic mass?

  0.99 x 12