why did bohr moel not work for bigger atoms

Thomson discovered the first subatomic particle: the electron. The most notable was his assertion that atoms were indivisible. Though revolutionary for its time, there were a few issues with Dalton’s atomic theory. Chemical reactions are best described by the rearrangements of different types of atoms in the reactants.Compounds are combinations of two or more types of atoms.Atoms of the same element are identical in terms of mass and chemical properties.All matter is composed of fundamental particles called atoms and these particles are indivisible.His atomic theory had four main assertions: While this knowledge is fundamental in our modern age, it took centuries of scientific research and experiments for us to understand how atomic structure works.Īlthough the ancient Greek philosopher, Democritus (460 – 370 BCE), was one of the first thinkers to propose the idea of an indivisible and fundamental particle called the atom (from the Greek word atomos, meaning indivisible), the modern day scientific theory of atomic structure only started in the early 1800s.Īs you can see from the timeline above, British scientist, John Dalton, was the first to propose a comprehensive scientific theory about the atom in 1803. We also know that an atom’s nucleus contains both protons (positively charged) and neutrons (negatively charged). Today, we know that the atomic structure involves negatively charged electrons orbiting a positively charged nucleus. Since ancient times, people have wondered what could be the most fundamental structure of physical reality, particularly that of matter. However, the model assumed electrons in the shells didn't interact with each other and couldn't explain why electrons seemed to stack in an irregular manner.Central to the development of chemistry as a scientific pursuit, rather than a mere philosophical proposition, is the idea of the atom and the knowledge of the atomic structure. It also explained why the noble gases were inert and why atoms on the left side of the periodic table attract electrons, while those on the right side lose them. For example, the shell model explained why atoms got smaller moving across a period (row) of the periodic table, even though they had more protons and electrons. The model explained some of the atomic properties of heavier atoms, which had never been reproduced before. Thus, the Bohr model for heavier atoms described electron shells. Once the level was full, additional electrons would be bumped up to the next level. Bohr believed each electron orbit could only hold a set number of electrons. More electrons were required to cancel out the positive charge of all of these protons. Heavier atoms contain more protons in the nucleus than the hydrogen atom.

Why did bohr moel not work for bigger atoms