Atomic Models Throughout History

The number of protons in an atom, determining its chemical identity.

The sum of protons and neutrons in an atom's nucleus, reflecting its mass.

Atoms of the same element with differing numbers of neutrons, resulting in different atomic masses.

Electrons in the outermost shell of an atom, involved in chemical bonding.

A rule stating that atoms tend to gain or lose electrons to achieve a stable configuration with eight electrons in their outermost shell.

The principle that matter cannot be created or destroyed in chemical reactions; it only changes form.

A compound always contains the same elements in fixed proportions by mass.

When two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a simple ratio.

The region where electrons are likely to be found within an atom, as described by Schrodinger's model.

The smallest particle of an element that can exist; the building block of all matter.

A subatomic particle carrying a positive charge, located in the atom's nucleus.

A subatomic particle with no charge, found in the atom's nucleus.

A negatively charged subatomic particle found orbiting the nucleus of an atom.

Proposed by J.J. Thomson, this model imagined atoms as spheres with positive charge uniformly distributed, with electrons scattered throughout like raisins in a pudding.

A Greek philosopher who proposed the idea that all matter is made up of small, indivisible particles called atoms. He believed that atoms were made of a single material and varied in shape and size to create different substances.

A British chemist credited with developing the first modern atomic theory. He proposed that all matter is made of atoms that are indivisible, indestructible, and combine to form new substances. He also suggested that atoms of the same element are identical, while atoms of different elements have different masses and sizes.

A New Zealand physicist who discovered the atom's nucleus, a dense, positively charged center. He also proposed that electrons orbit the nucleus like planets around the sun, though their exact positions are uncertain.

A Danish physicist who developed a model to explain the behavior of electrons in atoms. He proposed that electrons travel in specific orbits around the nucleus at fixed distances. He also suggested that electrons can jump between energy levels, absorbing or releasing energy.

An Austrian physicist who developed a model representing the probability of finding an electron at a specific location around the nucleus. This model showed that electron positions cannot be predicted with certainty, but instead, electrons exist as a cloud of probability.

The central part of an atom containing protons and neutrons. It is dense and positively charged due to the presence of protons.