Relative Masses and Charges of Protons, Neutrons and Electrons

Relative Masses and Charges of Protons, Neutrons and Electrons

Protons

• Protons are subatomic particles found in the nucleus of an atom.
• They have a positive charge (+1).
• The relative mass of a proton is 1 atomic mass unit (amu).

Neutrons

• Neutrons are also found in the nucleus of an atom.
• They are neutral, meaning they have no charge.
• Like protons, the relative mass of a neutron is 1 amu.

Electrons

• Electrons are found in shells orbiting the nucleus of an atom.
• They have a negative charge (-1).
• The relative mass of an electron is almost negligible, approximately 1/2000 amu.

Overall Atomic Structure

• An atom is composed of a central nucleus surrounded by electrons in shells.
• The nucleus contains both protons and neutrons, accounting for most of an atom’s mass.
• The number of protons in an atom is its atomic number and the total number of protons and neutrons is its mass number.
• Atoms are generally neutral because the number of negatively charged electrons is usually equal to the number of positively charged protons.