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Positively charge particle
Negatively charge particle
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Mesons
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1947
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Atoms are made out of three basic particles :
1. Protons – carry a positive charge
(Ernest Rutherford discovered the proton in 1911)
2. Neutrons – carry no charge
(James Chadwick contributed in the discovery of the neutron in
1932)
3. Electrons – carry a negative charge and circle the nucleus
(J. J Thomson discovered the electron in 1897 )
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Protons and neutrons are made up of smaller particles called
quarks.
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Quarks are held to each other by particles, scientists called it
gluons
• Mass of 1 proton = mass of 1836 electrons
• Neutrons and protons have almost the same mass
• Atoms always have as many electrons as protons
• Atoms usually have about as many neutrons as protons
e.g. Hydrogen (1 proton, 1 electron, 0 neutron) ; Helium (2 proton,
2 electron, 2 neutron) ; Carbon ( 6 proton, 6 electron, 6 neutron).
• Add a proton makes a new kind of atom
• Adding a neutron makes an isotope (Greek isos = equal, tópos = site,
place) of that atom, a heavier version of that atom. Isotope are any
of the different types of atoms (Nuclides) of the same chemical
element each having different atomic mass (mass number)