Development of atomic theory
Development of atomic theory
Dalton's atomic theory
Dalton's atomic theory
John Dalton developed an atomic theory in the 1800s. He did experiments,
John Dalton developed an atomic theory in the 1800s. He did experiments,
worked out some atomic weights and invented symbols for atoms and
worked out some atomic weights and invented symbols for atoms and
molecules. His most important conclusions are summarised below:
molecules. His most important conclusions are summarised below:

All matter is made of atoms

All matter is made of atoms

Atoms cannot be broken down into anything simpler

Atoms cannot be broken down into anything simpler

All the atoms of a particular element are identical to each other and

All the atoms of a particular element are identical to each other and
different from the atoms of other elements
different from the atoms of other elements
Dalton's theory was developed and changed as new evidence was
Dalton's theory was developed and changed as new evidence was
discovered.
discovered.
JJ Thomson's discovery of the electron
JJ Thomson's discovery of the electron
JJ Thompson discovered the electron in 1897. This showed that the atom
JJ Thompson discovered the electron in 1897. This showed that the atom
contained smaller pieces, whereas Dalton had thought that atoms could not
contained smaller pieces, whereas Dalton had thought that atoms could not
be broken down into anything simpler.
be broken down into anything simpler.
Rutherford's nuclear atom
Rutherford's nuclear atom
In 1911 Ernest Rutherford used experimental evidence to show that an
In 1911 Ernest Rutherford used experimental evidence to show that an
atom must contain a central nucleus. This was further evidence that an
atom must contain a central nucleus. This was further evidence that an
atom contained smaller pieces.
atom contained smaller pieces.
Bohr's electron orbits
Bohr's electron orbits
Niels Bohr further developed Rutherford's nuclear atom model. He used
Niels Bohr further developed Rutherford's nuclear atom model. He used
experimental evidence to support the idea that electrons occupy particular
experimental evidence to support the idea that electrons occupy particular
orbits or shells around the nucleus of an atom.
orbits or shells around the nucleus of an atom.
The development of the theory of atomic structure is an example of:
The development of the theory of atomic structure is an example of:

How a theory may change as new evidence is found

How a theory may change as new evidence is found

How a scientific explanation is provisional but may become more convincing

How a scientific explanation is provisional but may become more convincing
when predictions based on it are confirmed later on
when predictions based on it are confirmed later on
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/periodic_table/atomstrucrev5.sh
tml
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/periodic_table/atomstrucrev5.sh
tml