Overview
This lecture explains the three subatomic particles—protons, neutrons, and electrons—and their roles in determining an atom’s identity, mass, and charge.
The Three Subatomic Particles
- Atoms consist of protons, neutrons, and electrons, which are smaller than atoms themselves.
- Each subatomic particle plays a different role in the structure and behavior of the atom.
Protons
- Protons are located in the nucleus and determine the identity of the element.
- The atomic number of an element equals the number of protons in its nucleus.
- Changing the number of protons changes the element itself (e.g., oxygen has 8 protons, magnesium has 12).
Neutrons
- Neutrons are also in the nucleus and act as a buffer to reduce repulsion between positively charged protons.
- Neutrons contribute to the atomic mass.
- Changing the number of neutrons creates an isotope of the same element (mass changes, identity stays the same).
Electrons
- Electrons are found outside the nucleus in the electron cloud.
- Electrons control chemical reactivity and are responsible for the atom’s charge.
- Changing the number of electrons creates an ion (same element, different charge).
How Changing Particles Affects the Atom
- Changing protons: changes the element’s identity.
- Changing neutrons: changes the mass, creating isotopes.
- Changing electrons: changes the charge, creating ions.
Key Terms & Definitions
- Atom — smallest unit of matter that retains chemical properties.
- Proton — positively charged particle in the nucleus; defines the element.
- Neutron — neutral particle in the nucleus; affects mass and nuclear stability.
- Electron — negatively charged particle in the electron cloud; influences reactivity and charge.
- Isotope — atoms of the same element with different numbers of neutrons.
- Ion — atom with a net electrical charge due to loss or gain of electrons.
Action Items / Next Steps
- Review previous material on atoms, ions, and isotopes if needed.
- Watch suggested videos for calculating protons, neutrons, and electrons in atoms and ions.