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solid forms of matter are composed of indivisible elements shaped like triangles. -
atoms are uniform, solid, hard, incompressible, and indestructible and that they moved in infinite numbers through empty space until stopped. -
the four elements are not composed of atoms but were continuous forms of matter. -
everything is composed of very tiny particles, an idea known as atomism. -
the atom with the number of protons and neutrons in the nucleus, as well as the number of electrons in each of the electron shells. -
elements are arranged in increasing order of their atomic masses, the properties of the eighth element are a repetition of the properties of the first element. -
a periodic table of all the elements that were known at the time. -
the energy from photons is absorbed by matter, the matter can emit electrons. -
radiation was accidentally discovered when Henri Becquerel saw that uranium salts spontaneously emit a penetrating radiation that can be registered on a photographic plate -
the energy of light is proportional to frequency, and Planck's constant is the constant that relates them. -
the electrons are negatively charged particles embedded in a ton of positive charge. -
Small electrically charged drops of oil were suspended between two metal plates where they were subjected to the downward force of gravity and the upward attraction of an electrical field. -
this all showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus. -
The Bohr model postulates that electrons orbit the nucleus at fixed energy levels. Orbits further from the nucleus exist at higher energy levels. When electrons return to a lower energy level, they emit energy in the form of light -
the atomic number is the number of positive charges in the atomic nucleus. -
Hydrogen nuclei were observed by shooting alpha particles at a tube full of hydrogen and occasionally the alpha particle would knock a hydrogen nucleus out of the atom. Those nuclei hit detectors that gave off sparkling light when they were hit -
The transformation of the physical quantity overtime, where the quantum effects are like a wave-particle duality. -
you can either know how fast it is going, or where it's located, but not both at the same time without being uncertain. -
James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron. -
All metals were formed of sulfur and mercury in various proportions and that altering those proportions could transform the metal under study.