Atomic Structure: Historical Perspective

• Rutherford’s model (solar system)
• stated that the atom is mostly empty space with a dense center of mass (nucleus) and circling electrons.
• proposed that the nucleus had a particle that had the same amount of charge as an electron but the opposite sign.
• These particles are called protons.
• charge = +1.60 × 1019 C
• mass = 1.67262 × 10−24 g
• Since protons and electrons have the same amount of charge, for the atom to be neutral, there must be equal numbers of protons and electrons.