Atoms and the periodic Table Flashcards
Order of the scientists who came up with theories of the Atom:
1.John Dalton
2.Thomson
3. Rutherford
4.Bohr
5. James Chadwick
John Dalton
published his ideas about atoms in 1803. He thought that all matter was made of tiny particles called atoms, which he imagined as tiny spheres that could not be divided.
JJ Thomson
Nearly 100 years after Dalton’s idea, carried out experiments and discovered the electron. This led him to suggest the plum pudding model of the atom, it is were the atom is a ball of positive charge with negative electrons embedded in it - like currants in a pudding.
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Rutherford
He did experiment to test the plum pudding model. positively charged alpha particles were fired at thin gold foil. Most alpha particles went straight through the foil. But a few were scattered in different directions. His evidence made him suggest a new model for the atom, called the nuclear model. In the nuclear model:
-There is a nucleus in the center were the mass is concentrated
- The nucleus is positively charged
Neil’s Bohr
Bohr did calculations that led him to suggest that electrons orbit the nucleus in shells. The shells are at certain distances from the nucleus. Further experiments led to the idea that the nucleus contained small particles, called protons. Each proton has a small amount of positive charge.
James Chadwick
In 1932, he found evidence for the existence of particles in the nucleus with mass but no charge. These particles are called neutrons. This led to another development of the atomic model, which is still used today.
Subatomic particle with their relative Mass and Relative charge
Protons: Relative Mass - 1
Relative Charge - +1
Neutron: Relative Mass - 1
Relative Charge - 0
Electron: Relative Mass - very
small
Relative Charge - -1
Do Atoms have a overall charge, explain why.
No because they contain an equal number of protons and electrons.
Atoms don’t have the same number of protons. True/False.
False, they do have the same number of protons as long as they are in the same element.
What is the number of protons in an atom called?
Atomic number
What is the sum of the protons and neutrons in an atom?
Mass number
Equation to work out the number of neutrons
Mass number - atomic number
Isotope
An element that have the same number of protons but a different number of neutrons. E.g:
35 {17 Protons}
CI {17 electrons}
17 {18 neutrons (35-17)}
To become an ion, what can atoms do?
They can gain or lose electrons.
How does metal atoms become ions?
They lose electrons to form positive ion.
