They are called isotopes.
Isotopes have the same number of electrons and protons in their unionized state. They differ in the number of neutrons. The first and simplest example is hydrogen.
The most common hydrogen has
1 proton
1 electron and
0 neutrons
It has 2 cousins
1 proton
1 electron
1 neutron
And
1 proton
1 electron
2 neutrons.
Most elements have some differences in the number of neutrons present in their nuclei. Cesium and Xenon have the most number of isotopes. Each has 36. You wonder how the atoms are held together.
Answer: 1
1.Cl K Ar is in order
2.Fe Co Ni isn't in order
3.Te I Xe isn't in order
4.Ne F Na isn't in order
87.8 , 31 Celsius=87.8(88) in Fahrenheit
