Why is each nuclide shown unstable?

Question

33 64 223
CI Cu Fr
17 29 87

Answer 1

Cl-33 has too few neutrons for the 17 protons, so it will decay by positron emission. 17 Cl 33 ===> e+ + 16 S 33 Some neutron-poor isotopes like thallium-201 decay by electron capture. The nucleus sucks a K-shell electron inside where it combines with a proton to become a neutron. Electron capture is rare.

Cu-64 has too many neutrons, so it decays by beta emission. 29 Cu 64 ===> e- + 30 Zn 64

Fr-223 is just too heavy to be stable, as are all isotopes of all elements above Bi, No. 83. Such elements decay by alpha emission. 87 Fr 223 ===> 2He4 + 85Bi219

Answer 2

they don't have a complete outer shell of 7 electrons in their orbit. they need to combine either covalently or ionically with another element to make their 7 quoto and become stable compounds.

Answer 3

Large differences in the number of neutrons and protons. If the ratio of protons to neutrons is one or near one the isotope is less likely to be unstable, and the nuclei of stable isotopes can hold together.