How many nucleons are present in an atom of Nobelium, N o 102 254 ? How many electrons are present in the atom? How many nucleons may be considered as neutrons?

Number of nucleons = Mass number Thus, number of nucleons = 254 Number of electrons = Number of protons = Atomic number Thus, number of electrons = 102 Now, number of neutrons = Mass number – Atomic number = 254 - 102 = 152

Complete the following table: Particle Atomic Number Mass Number Number of electrons Number of protons Number of neutrons Sodium atom 11 12 Aluminium ion 27 10 Chloride ion 18 18 Phosphorus atom 31 15 Cuprous iron 28 35

Atomic number = No.of electrons = No.of protons. Mass number = No.of protons + No.of neutrons. Using the above two formulae calculated the missing values in the table given in question. Particle Atomic Number Mass Number Number of electrons Number of protons Number of neutrons Sodium atom 11 23 11 11 12 Aluminium ion 13 27 10 13 14 Chloride ion 17 35 18 17 18 Phosphorus atom 15 31 15 15 16 Cuprous iron 29 64 28 29 35

Complete the following table: Name of the Particle Mass Number Atomic Number Protons Number of Electrons Neutrons Oxygen 8 8 Sodium ion 23 11 Bromine 35 45

For Oxygen, Atomic number = No.of electrons = No.of protons = 8 . Mass number = No.of protons + No.of neutrons = 8 + 8 = 16 . For Sodium ion, Atomic number = No.of electrons = No.of protons = 11 . No.of neutrons = Mass number - Atomic number = 23 - 11 = 12 . For Bromine, Atomic number = No. of protons = No.of electrons = 35 . Mass number = No.of protons + No.of neutrons = 35 + 45 = 80 . Name of the Particle Mass Number Atomic Number Protons Number of Electrons Neutrons Oxygen 16 8 8 8 8 Sodium ion 23 11 11 10 12 Bromine 80 35 35 35 45

Find the number of protons, electrons and neutrons in a A l 3 + 13 27 b O 2 - 8 15 .

a Number of protons = 13 . Number of neutrons = Mass number - Atomic number = 27 - 13 = 14 . As, aluminium has + 3 charge, Number of electrons = 13 - 3 = 10 . b Number of protons = 8 . Number of neutrons = Mass number - Atomic number = 15 - 8 = 7 . As, oxygen has - 2 charge, Number of electrons = 8 + 2 = 10 .