Atomic Theory Flashcards

Flashcards on Atomic Theory

Atomic Theory (Ancient Beginnings)

The idea that matter is composed of indivisible units called 'atomos'.

Democritus

An ancient Greek philosopher who first proposed the idea that matter is not infinitely divisible and introduced the concept of atoms.

Aristotle

An ancient Greek philosopher who believed empty space could exist, thought matter was continuous, and did not believe in the atom; he proposed that matter consisted of Earth, Fire, and Water.

Solid Sphere Model

Atoms are dense and solid, with no internal structure or subatomic particles.

Plum Pudding Model

Atoms are uniform, positively charged spheres with electrons embedded within them.

Nuclear Model

Atom consists of a small, dense, positively charged nucleus at the center, with electrons orbiting around it.

Planetary Model

Electrons move in quantized, discrete energy levels around the nucleus and emit or absorb energy when transitioning between levels.

Quantum Model

Electrons do not have definite orbits, but are described by wave functions representing probability distributions of their locations.

John Dalton

Proposed the Solid Sphere Model in the early 19th century, shifting from philosophical ideas to scientific theory based on experimental evidence.

Solid Sphere Model Postulates

All matter is made of atoms, atoms in an element are identical, atoms combine to make compounds, and atoms cannot be created or destroyed.

J.J. Thomson

Proposed the Plum Pudding Model in the late 19th century and discovered electrons as distinct particles.

Plum Pudding Model Theory

Atoms are like plum pudding, with tiny negative charges scattered throughout a cloud of positive electrons.

Ernest Rutherford

Used the Gold Foil Experiment and introduced the Nuclear Model in the early 20th century.

Nuclear Model Theory

Atoms have a nucleus with a positive charge and most of the mass, surrounded by electrons that orbit like planets.

Niels Bohr

Proposed the Planetary Model in the early 20th century, explaining atomic spectra and introducing energy levels.

Planetary Model Theory

Electrons orbit the nucleus in specific energy levels or shells.

James Chadwick

Worked with Rutherford and discovered the neutron in 1932; neutrons have no charge and have approximately the same mass as protons.

Erwin Schrödinger

Proposed the Quantum Model in the 1920s, providing a comprehensive understanding of electron behavior using quantum mechanics.

Quantum Model Theory

Electrons exist as a probable wave-like pattern around the nucleus, not in a specific orbit.

Modern Atomic Model

The nucleus is a dense region with protons and neutrons, and electrons are found in the electron cloud in random motion.