This subatomic particle carries a negative charge and orbits the nucleus.
What is an electron?
This ancient Greek philosopher first proposed the idea of indivisible particles called "atomos."
Who is Democritus?
Ernest Rutherford fired alpha particles at this incredibly thin material to discover the atomic nucleus.
What is gold foil?
This planetary-style model, developed in 1913, depicts electrons traveling around the nucleus in fixed, circular orbits.
What is the Bohr Model?
his fundamental force of nature overcomes electrical repulsion to glue protons and neutrons together in the nucleus.
What is the strong nuclear force?
These two subatomic particles make up the dense nucleus at the center of an atom.
What are protons and neutrons?
In 1803, this English chemist formulated the first modern atomic theory, viewing atoms as solid, indivisible spheres.
Who is John Dalton?
J.J. Thomson's atomic model, featuring negative electrons scattered inside a positive sphere, is famously named after this festive English dessert.
What is the Plum Pudding model?
he modern atomic model does not track exact electron paths; instead, it predicts their location within this regional "cloud."
What is the electron cloud model (or Quantum Mechanical model)?
This term describes the specific amount of time it takes for half of a radioactive sample's atoms to decay.
What is a half-life?
This number, found on the periodic table, represents the exact number of protons in an atom's nucleus.
What is the atomic number?
J.J. Thomson discovered the electron in 1897 using this specialized, vacuum-sealed glass tube equipment.
What is a cathode-ray tube?
Robert Millikan determined the exact charge of a single electron in 1909 by spraying this liquid mist into an electric field.
What is oil? (The Oil-Drop Experiment)
This principle states that it is physically impossible to simultaneously know both the exact position and momentum of an electron.
What is the Heisenberg Uncertainty Principle?
This type of radioactive decay occurs when an unstable nucleus emits a particle identical to a Helium-4 nucleus.
What is alpha decay?
This term describes atoms of the same element that have the same number of protons but a different number of neutrons.
What is an isotope?
This scientist discovered the neutron in 1932, completing the basic picture of the atom's nucleus.
Who is James Chadwick?
Because most alpha particles passed straight through the gold foil in Rutherford's experiment, he concluded that the atom is mostly made of this
What is empty space?
These specific, outermost electrons determine an atom's chemical properties and how it bonds with other atoms.
What are valence electrons?
Protons and neutrons are not fundamental; they are made up of smaller elementary particles given this quirky, 5-letter name.
What are quarks?
Because electrons are so incredibly small, this subatomic particle is the lightest, weighing roughly 1/1,836 the mass of a proton.
What is the electron?
This French physicist proposed in 1924 that moving particles like electrons can behave like waves, a milestone for quantum theory.
Who is Louis de Broglie?
This famous 1927 thought experiment features a feline that is simultaneously alive and dead to illustrate the strange nature of quantum superposition.
What is Schrödinger's Cat?
These mathematical values (represented by letters like n, l, and m) act like a coordinate system or "home address" for an electron.
What are quantum numbers?
n beta-minus decay, a neutron inside the nucleus transforms into a proton while ejecting an electron and this ghost-like, neutral particle
What is an antineutrino?