wunder beta⚛️ Atoms & Molecules
Zoom into the almost-empty building blocks that make up everything you touch.
What you’ll learn
- Describe the three subatomic particles and the atom's dense nucleus surrounded by empty space.Atoms are the smallest units of elements, made of protons, neutrons, and electrons. Protons define the element. Nearly all mass sits in a tiny nucleus, while the electron cloud makes matter mostly empty space.
- Explain electron shells, valence electrons, isotopes, and ions.Electrons occupy quantized shells, and outer valence electrons drive chemistry. Isotopes differ in neutron count, while ions form when atoms gain or lose electrons, creating charge and enabling ionic attraction.
- Explain how atoms bond into molecules and what lies inside protons and neutrons.Atoms bond covalently, ionically, or metallically to form molecules and materials. Protons and neutrons are made of quarks bound by gluons. Combining fewer than a hundred atom types builds the whole material world.
Questions this course answers
Which subatomic particle determines which element an atom is?
The number of protons, the atomic number, defines the element's identity.
Where is nearly all of an atom's mass concentrated?
Protons and neutrons in the tiny nucleus hold more than 99.9 percent of the atom's mass.
Why is it said that atoms are mostly empty space?
The nucleus is minuscule compared to the vast volume occupied by the electron cloud.
Valence electrons are important because they:
Outer-shell valence electrons drive how atoms bond and react.
Two atoms of the same element with different numbers of neutrons are called:
Isotopes share proton count but differ in neutrons, giving different masses.
An atom that has lost one or more electrons becomes:
Losing electrons leaves more protons than electrons, creating a positively charged cation.
Grounded in trusted sources
- Britannica, 'Atom' (britannica.com/science/atom)
- Chemistry LibreTexts, 'Structure of an Atom' (chem.libretexts.org)
- Feynman, Richard P., 'Six Easy Pieces' (Basic Books, 2011)
- Nature Education Scitable, 'Discovery of the Atomic Nucleus' (nature.com/scitable)
Every Wunder lesson is built from real, reputable sources — never invented.
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