Atomic Structure

               Charge         Mass

Proton      1+                 1.0

Neutron     1-                  1.0

Electron     0                  1/2000

• Protons and neutrons make up the nucleus
• Electrons orbit the nucleus in shells (energy levels)

• Nucleus is tiny compared to the volume of the atom
• Nucleus is extremely dense. makes up most of mass

atoms of the same element with

Mass

• number of neutrons in the nucleus
•  

Same

• number of protons
• number of electrons

Different isotopes of an element react in the same way. Because:

• chemical reactions involve electrons
• neutrons make no difference in chemical reactivity

Atom: Al (13)

• Atomic no. -- 13
• Mass no. -- 27
• Protons -- 13
• Neutrons -- 14
• Electrons -- 13
• Charge -- 0

Ion: Al 3- (10)

•  
  • Atomic no. -- 10
  • Mass no. -- 27
  • Protons -- 13
  • Neutrons -- 14
  • Electrons -- 10
  • Charge -- 3-