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Introduction to the Atom. Protons, neutrons, electrons and the nucleus. What is an atom?. An atom is the smallest particle of an element that can be broken down and still have the characteristics of that element Basic building block of matter. The Nucleus.
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Introduction to the Atom Protons, neutrons, electrons and the nucleus
What is an atom? An atom is the smallest particle of an element that can be broken down and still have the characteristics of that element Basic building block of matter
The Nucleus The nucleus of an atom is the positive dense core of the atom. Contains more than 99% of the atom’s mass.
3 Subatomic Particles • Atoms are composed of 3 subatomic particles: • Protons • Neutrons • Electrons
The Electron Negatively charged subatomic particle Discovered in 1897 by J.J. Thomson Symbol: e- Charge = -1 In constant motion orbiting nucleus
Protons • Positively charged subatomic particles • Discovered by Ernest Rutherford • Charge is equal but opposite that of an electron • Charge = +1 • Symbol: p+ • Located in nucleus
Neutrons Subatomic particle with no charge (neutral) Discovered by James Chadwick Mass equal to proton’s symbol : n0 Charge = 0 Located in nucleus