Atom and Nucleus

8.2  Atom and Nucleus

Atomic structure:

  • The development of atomic structure is said to have begun when John Dalton introduced the Atomic Theory

  • Dalton's Atomic Theory states that atoms are the smallest particles and there are three subatomic particles that make up an atom, namely protons, neutrons, and electrons

Subatomic particles

Features

Proton

  • Positively charged

  • Inside the atomic nucleus

Neutron

  • Not charged (neutral)

  • Inside the atomic nucleus

Electron

  • Negatively charged

  • Inside the atomic nucleus

 

Ion formation:

  • Ions are formed when atoms lose (positive ions) or receive electrons (negative ions)

  • Positive ions are formed when atoms lose electrons. So a positive ion has more protons than its number of electrons

  • Negative ions are formed when atoms receive electrons. Thus, a negative ion has more electrons than its number of protons