Development of the atomic theory

Periodic Table

• is a representation of all elements that man has encountered throughout time

Dmitri Mendeleev

• a Russian chemist in 1869.

• recognized the arrangement of elements in the periodic table reflects the properties of the elements

Robert Boyle

• critical of the ideas of alchemy

• supports the corpuscular theory wherein all forms of matter are composed of minute particles.

• corpuscles were certainly primitive and simple, unmingled indivisible bodies

• suggests that observation and testing are two important features of an experiment

• his experiment is called "mechanical philosophy.

Elements

• simplest unit of substances

• cannot be simplified or decomposed into simpler substances through any chemical reaction.

Antoine Lavoisier

• demonstrated the Law of Conservation of Mass

• phlogiston theory

• air is not an element but a mixture of different gases

• water is not an element but a compound composed of hydrogen and oxygen.

• able to identify 33 elements

• wrote the first chemistry textbook

Traite Elementaire De Chimie

• 33 elements and wrote the first chemistry textbook

Johann Becher

• phlogiston theory

Phlogiston Theory

• combustion of materials led to a release of a fire-like element called phlogiston.

Phlogiston

• fire-like element

Democritus

• concept of atomism

John Dalton

• published his atomic theory in 1808.

• each has its own postulates

• law of definite proportion

• law of multiple proportions

Joseph Gay-Lussac

• oxygen exist in molecular form than single free atom

Amedeo Avogrado

• masses of atoms and molecules can be determined through gasses

Period

• horizontal alignment of elements

Group

• vertical alignment of elements