Study Notes
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers. They have the same chemical properties due to identical electronic configurations.
- Isotopes — different atoms of the same element with the same number of protons but different numbers of neutrons. Example: Carbon-12 and Carbon-14 are isotopes of carbon.
- Relative Atomic Mass (Ar) — the average mass of an element's isotopes compared to 1/12th of the mass of a carbon-12 atom. Example: Chlorine has a relative atomic mass of 35.5.
- Chemical Properties — characteristics that remain the same for isotopes of the same element due to identical electron configurations. Example: All isotopes of hydrogen react similarly with oxygen.
- Physical Properties — characteristics that may vary between isotopes due to differences in mass. Example: The density of Uranium-235 differs from Uranium-238.
Exam Tips
Key Definitions to Remember
- Isotopes: Atoms of the same element with different numbers of neutrons.
- Relative Atomic Mass: The weighted average mass of an element's isotopes compared to carbon-12.
Common Confusions
- Confusing atomic number with mass number.
- Assuming isotopes have different chemical properties.
Typical Exam Questions
- What are isotopes? Atoms of the same element with different numbers of neutrons.
- How do you calculate the relative atomic mass? By averaging the masses of isotopes based on their abundance.
- Why do isotopes have the same chemical properties? Because they have the same number of electrons and electronic configuration.
What Examiners Usually Test
- Understanding of isotopes and their properties.
- Ability to calculate relative atomic mass.
- Knowledge of how isotopes affect physical properties.