Development of the Atomic Theory and States of Matter

Vocabulary flashcards covering states of matter, phase changes, subatomic particles, and key historical figures in the development of atomic theory.

Solid

A state of matter where particles are tightly packed in regular rows and vibrate slowly in fixed positions, resulting in a fixed shape and fixed volume.

Liquid

A state of matter where particles have small gaps and slide past each other slowly, resulting in a fixed volume but no fixed shape.

Gas

A state of matter where particles have lots of space and move rapidly and freely, resulting in no fixed shape and no fixed volume.

Melting

The phase change where a solid gains heat and turns into a liquid.

Freezing

The phase change where a liquid loses heat and turns into a solid.

Evaporation

The phase change where a liquid gains heat and turns into a gas.

Sublimation

The phase change where a solid directly turns into a gas.

Condensation

The phase change where a gas turns into a liquid.

Deposition

The phase change where a gas directly turns into a solid.

Atom

The basic unit of matter.

Subatomic

Particles that are unbelievably bitsy and tinier than ordinary matter.

Nucleus

The organized sphere at the center of an atom housing the heavy particles, including protons and neutrons.

Electron

Negatively charged subatomic particles that rotate outside the nucleus and emit energy or light.

Proton

Positively charged subatomic particles residing in the nucleus.

Neutron

Subatomic particles carrying no charge found inside the region of the nucleus.

Democritus

An Ancient Greek philosopher from 400 BCE who used philosophical guessing to propose that all matter is made of tiny, indivisible particles called atomos.

Atomos

A Greek term meaning "uncuttable", used by Democritus to describe invisible particles moving through empty space.

Indivisible Particle Model

The atomic model proposed by Democritus in 400 BCE suggesting that atoms come in different shapes such as squares and triangles.

Aristotle

A famous ancient Greek philosopher who rejected Democritus's idea of atoms and believed matter was continuous and made of four basic elements: Terra (Earth), Aqua (Water), Aer (Air), and Ignis (Fire).

John Dalton

An English schoolteacher and chemist of the early 1800s who used scientific experiments with gases and chemicals to formulate the first modern atomic theory.

Solid Sphere Model

John Dalton's atomic model proposing that matter is made of solid, indivisible sphere atoms, and that atoms of the same element are exactly alike.