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Period: 440 BCE to
Democritus Model
He stated that atoms are indestructible and unchangeable. His atomic model was solid.
Used the term indivisible (atom) for the first time. Attributed popular belief in the gods to a desire to explain extraordinary phenomena (thunder, lightning, earthquakes). He explained the origin of the universe as follows. How the model was wrong? He suggested that atoms were eternal and could not be destroyed. -
Period: to
Dalton ‟Billiard ball" Model
Atoms were solid spheres indivisible and indestructible. He envisioned them as solid, hard spheres, like billiard (pool) balls. John Dalton is also credited with developing laws for understanding how gases work. He stated that elements combine at the atomic level in fixed ratios which naturally differ based on the compounds being combined, due to their unique atomic weights. How was the model wrong? Scientists discovered that the atom can be subdivided into even smaller elementary particles. -
Period: to
Thompson Model
Consisted of an spherical cloud that is positively charged and inside of it there are electrons, that are negatively charged. He discovered the existence of the electron in the composition of the atom, he earned a Nobel Prize in Physics due to this. His discovery led to new ways of understanding electricity and atomic particles, isotopes and others. How was the model wrong? He assumed that the electrons were uniformly distributed and free to rotate in rings inside a sphere of positive charge. -
Period: to
Rutherford Model
The model described the atom as a tiny, dense, positively charged core called a nucleus, also called nuclear atom or planetary model of the atom. He devoted himself to the study of radioactive particles and managed to classify them into alpha (α), beta (β) and gamma (γ). -
Period: to
Bohr Model
Has an atom consisting of a small, positively charged nucleus orbited by negatively charged electrons. Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element. How was the model wrong? It does not account for sublevels (s,p,d,f), orbitals or electron spin. -
Period: to
Schrödinger Model
Energy levels are divided into sublevels and sublevels into orbitals. He used mathematical equations to describe the likelihood of finding an electron in a certain position. Where the cloud is most dense, the probability of finding the electron is greatest, and conversely, the electron is less likely to be in a less dense area of the cloud. This model introduced the concept of sub-energy levels. This is the recent atomic model accepted and they have no find any error in this model