Summary
Atomic structure involves understanding the arrangement of electrons, protons, and neutrons within an atom. Isotopes are atoms of the same element with different numbers of neutrons, affecting their physical but not chemical properties.
- Atom — the smallest unit of an element, consisting of a nucleus surrounded by electrons. Example: Hydrogen atom
- Proton Number — also known as atomic number, it is the number of protons in the nucleus of an atom. Example: Carbon has a proton number of 6.
- Nucleon Number — also known as mass number, it is the total number of protons and neutrons in the nucleus. Example: Carbon-12 has a nucleon number of 12.
- Isotopes — atoms of the same element with the same number of protons but different numbers of neutrons. Example: Carbon-12 and Carbon-14
- Mass Spectra — a graph showing the distribution of ions by mass in a sample. Example: Mass spectrum of chlorine showing peaks for Cl-35 and Cl-37.
Exam Tips
Key Definitions to Remember
- Atom
- Proton Number
- Nucleon Number
- Isotopes
Common Confusions
- Confusing proton number with nucleon number
- Assuming isotopes have different chemical properties
Typical Exam Questions
- What is the proton number of an element? The number of protons in the nucleus.
- How do isotopes of an element differ? They have different numbers of neutrons.
- How is relative atomic mass calculated? By using the relative abundance of isotopes.
What Examiners Usually Test
- Understanding of atomic structure and electron arrangement
- Ability to calculate relative atomic mass from isotopic data
- Interpretation of mass spectra