HIGHLIGHTS OF THE EVOLUTION OF ATOMIC STRUCTURE

Question 1

Many believed that matter was continuous – that is, that it could be divided infinitely.

Answer 1

Aristotle BEFORE 19TH CENTURY

Question 2

� Elements can combine in
different ways to form
different compounds,
whose mass ratios are
simple whole-number
multiples of each other.

Answer 2

Law of Multiple Proportion

Question 3

Seen by the eyes of human

Answer 3

MACROSCOPIC

Question 4

If you took the substance and divided it enough, eventually you’ll get the smallest particle of it (450 BC)

Answer 4

Democritus BEFORE 19TH CENTURY

Question 5

Seen deeply to the atoms

Answer 5

SUBMICROSCOPIC

Question 6

Proposed by Antoine Lavoisier in 1787.
Mass is not gained or lost in a chemical
reaction

Answer 6

Law of Conservation of Mass

Question 7

Proposed by Joseph Proust
between 1797 and 1804
A compound always has
the same relative amounts
of the elements that
compose it

Answer 7

Law of Definite Proportion

Question 8

POSTULATES OF DALTON’S ATOMIC THEORY 1

Answer 8

All matter is composed of exceedingly small, indivisible particles, called
atoms.

Question 9

POSTULATES OF DALTON’S ATOMIC THEORY 4

Answer 9

Atoms combine in simple, fixed, whole-number ratios to form compounds.
All water molecules have the same proportion by mass. In the above figure, river water, rainwater, and tap water have a fixed composition of hydrogen 11.11 % and oxygen 88.89 %.

Question 10

In 1808 John Dalton published a paper on atomic theory

summarizing the characteristics of atoms into postulates.

Answer 10

DALTON’S ATOMIC THEORY

Question 11

POSTULATES OF DALTON’S ATOMIC THEORY 3

Answer 11

Atoms are not created or destroyed in chemical reactions

Question 12

Seen through a microscope

Answer 12

MICROSCOPIC

Question 13

POSTULATES OF DALTON’S ATOMIC THEORY 2

Answer 13

All atoms of a given element are identical both in mass and in chemical properties.
Atoms of different elements have different masses and different chemical
properties