1.6 Relative atomic mass

• What is relative atomic mass compared to 1/12 the mass of a carbon-12 atom?

  Average mass of an atom
• The atomic mass is the actual mass of an atom in grams
• Steps to calculate relative atomic mass:

  1️⃣ Identify the isotopes of the element

  2️⃣ Determine the mass of each isotope

  3️⃣ Determine the abundance of each isotope

  4️⃣ Apply the formula: Ar = (Isotope mass × Isotope abundance) / 100
• To calculate relative formula mass, you first use the relative atomic mass values from the periodic table
• Match the concept with its definition:

  Relative atomic mass ↔️ Average mass of an atom compared to 1/12 mass of carbon-12

  Atomic mass ↔️ Actual mass of an atom in grams

  Atomic weight ↔️ Average mass of an element's atoms compared to 12C
• Relative atomic mass reflects isotopic abundance.


  True
• Relative atomic mass highlights differences between individual isotopes and overall elemental averages
• Relative atomic mass has units.

  False
• Why is relative atomic mass a useful measure?

  Compares masses of elements
• What is relative atomic mass essential for calculating?

  Relative formula mass
• What are the two isotopes of chlorine and their abundances?

  Cl-35 (75%) and Cl-37 (25%)
• What is the relative formula mass of CO2?

  44.0
• The relative atomic mass of chlorine is 35.5.


  True
• Match the compound with its relative formula mass:

  CO2 ↔️ 44.0

  H2O ↔️ 18.0

  NaCl ↔️ 58.5