Overview
This lecture explains the concept of Relative Atomic Mass, using real-life examples and connecting them to the chemical standard based on carbon-12.
Understanding Relative Atomic Mass
- Relative means comparing one quantity to a standard reference.
- In chemistry, the standard for atomic mass comparison is a portion of the carbon-12 isotope.
- This is similar to using known weights to measure vegetables at a shop.
Standard Reference in Chemistry
- Chemists use the carbon-12 isotope as the standard for atomic masses.
- Carbon-12 is chosen because it is the most abundant and stable isotope of carbon.
- Carbon-13 and carbon-14 are other isotopes, but carbon-12 is the reference.
Defining Relative Atomic Mass
- Relative Atomic Mass is the ratio of the mass of an atom to 1/12th the mass of a carbon-12 atom.
- The process involves dividing a carbon-12 atom into 12 equal parts and using one part as the unit of comparison.
Atomic Mass Unit (AMU)
- One atomic mass unit (amu) is defined as exactly 1/12th the mass of a carbon-12 atom.
- AMU provides a unified standard for measuring atomic masses of different elements.
Key Terms & Definitions
- Relative Atomic Mass — The mass of an atom compared to 1/12th the mass of a carbon-12 atom.
- Isotope — Different forms of the same element with varying numbers of neutrons.
- Atomic Mass Unit (AMU) — The mass equal to 1/12th of a carbon-12 atom.
Action Items / Next Steps
- Review the concept of isotopes and their significance in atomic mass calculations.
- Memorize the definition of Relative Atomic Mass and Atomic Mass Unit.