Atomic number (Z): (from the periodic table)"
• represents the identity of the element
• reveals the number of protons
• in a neutral element:
# of protons = # of electrons
Mass number (A)
• reveals the number of protons and neutrons
mass number = # of protons + # of neutrons
Element: Se (selenium)
atomic number = 34
# of electrons = 34
# of protons = 34
# of neutrons = mass number – # of protons
# of neutrons = 77 – 34
# of neutrons = 43
# of protons = mass number – # of neutrons
# of protons = 65 – 36
Fill in the missing information for the neutral isotopes in the table below
Number of neutrons:
Number of protons:
Number of electrons:
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