Protons, Neutrons & Electrons

• Charge can be positive or negative
• Protons, neutrons and electrons have different properties and different charges

  • Protons have a positive charge
  • Electrons have a negative charge
  • Neutrons have no charge
• Relative charge can be used to compare these properties

  • Relative charge is the ratio of the charge of a particle compared to the fundamental charge
  • Because relative charge is a ratio, it has no units
• Fundamental charge is equal to the magnitude of the charge on a proton and an electron = 1.6 × 10−19 C
• The relative charge of a proton is:

  • 1.6 x 10^-9 C/ 1.6 x 10^-9C = +1
• The relative charge of an electron is:

  • -1.6 x 10^-19 C / 1.6 x 10^-19 C = -1
• The relative charge of a neutron is:

  • 0C/ 1.6 x 10^-19 C - 0
• Table of relative charges

  A) +1

  B) 0

  C) -1

  
• You don't need to know how to calculate relative charge, but you do need to understand what it is

  • You do also need to remember what the relative charges are for each subatomic particle.
• Nuclear charge is the relative charge of the nucleus

  • This is determined by the proton number of the atom
• Relative charge is calculated by:

  • nuclear charge = number of protons in the nucleus x relative charge of a proton
• Charge can be either positive (+) or negative (–)

  • Usually, when a number is positive, we don't write the + sign, but when dealing with relative charge, we do
• Nuclear mass or the relative mass of an atom, is the relative mass of the nucleus

  • This is because the mass of electrons orbiting the nucleus is negligible
• A relative mass of 1 = 1.67 × 10^-27 kg
• The relative mass of an atom is determined by the nucleon number of the atom

  • relative mass of atom = number of protons andd neutrons in the nucleus x relative mass of a proton or neutron
• An element of carbon has a nucleon number of 12

  • So the relative mass of carbon is 12 × 1 = 12 atomic mass units or amu
• Table of relative mass

  A) 1

  B) 1

  C) 1/2000

  D) negligible