Relative masses

• What is the purpose of relative masses in chemistry?

  To compare the mass of atoms, elements, and compounds
• Why is relative atomic mass useful?

  It compares masses of different elements
• How is relative atomic mass defined?

  Mean mass of atoms compared to carbon-12
• Where can relative atomic mass values be found?

  On the periodic table in exam papers
• What does relative molecular mass refer to?

  Mass of molecules with simple covalent structures
• How is relative molecular mass calculated?

  Sum of relative atomic masses of all atoms
• What is relative formula mass used for?

  Referring to substances with giant structures
• How can relative atomic masses be used in calculations?

  To calculate relative molecular masses of molecules
• What is the relative molecular mass of ethanol, C₂H₅OH?

  46.0
• How is the relative molecular mass of ethanol calculated?

  By summing masses of 2 C, 6 H, and 1 O
• What is the relative molecular mass of hydrated copper sulfate, CuSO₄.5H₂O?

  249.6
• How is the relative molecular mass of CuSO₄.5H₂O calculated?

  By summing masses of Cu, S, O, and H₂O
• What units do relative masses have?

  They do not have units
• Why is it helpful to show all stages of working in calculations?

  It aids in understanding complex compounds
• To what decimal place are values from the periodic table typically given?

  One decimal place
• What does the notation 5H₂O indicate in a formula?

  Five water molecules are attached
• What does it mean for crystals to be hydrated?

  They contain water molecules attached
• What is the precise value for sulfur's atomic mass?

  32.1
• Why should precise values from the periodic table be used?

  To ensure accuracy in calculations