Respuesta :

Edufirst

Answer:

The missing nucleus is carbon-12:

  • [tex]^{12}_6C[/tex]

Explanation:

The nuclear reaction given is:

[tex]^{249}_{98}Cf[/tex] + ___ → [tex]^{257}_{104}Rf+4^1_0n[/tex]

To balance this equation you must add a nucleus which contains the missing mass and atomic numbers.

Mass number is the number of protons plus neutrons and is the superscript to the left of the chemical symbol: 249 for Cf, 257 for Rf, and 1 for n (neutron).

Atomic number is the number of protons and is the subscript to the left of the chemical symbol: 98 for Cf, 104 for RF and 0 for n.

Thus, the balance is:

Mass number:

  • 249 + A = 257 + 4 × 1
  • 249 + A = 257 + 4
  • 249 + A = 261
  • A = 261 - 249
  • A = 12

Atomic number:

  • 98 + Z = 104 + 4×0
  • 98 + Z = 104
  • Z = 104 - 98
  • Z = 6

Then, you are looking for a nucleus (or gropu of nuclei) which supply 6 protons and 6 neutrons. That is a nucleus of carbon-12: [tex]^{12}_6C[/tex].

The balanced nuclear reaction is:

[tex]^{249}_{98}Cf+^{12}_{6}C[/tex] → [tex]^{257}_{104}Rf+4^1_0n[/tex]