The formula is Atomic Mass (rounded to the nearest whole number) minus the Atomic Number.
This works because Protons and Neutrons have virtually the same mass, and electrons virtually none. As well as the Atomic Number being equal to the amount of Protons.
Essentially:
Protons + Neutrons - Protons = Neutrons. Basic Prealgebra.
So to find the amount of Neutrons in Erbium:
Erbium's Atomic Mass rounded (167) - Erbium's Atomic Number (68) = approx. 99 Neutrons
All erbium ordinarily found in nature is of stable isotopes. Like all other elements, erbium has synthetic radioactive isotopes.
The difference among the five isotopes of Erbium (164Er, 166Er, 167Er, 168Er, and 170Er) lies in their number of neutrons. While all isotopes have the same number of protons (68), the varying neutron counts result in different atomic masses. This variance in neutron number also contributes to differences in nuclear stability and some physical properties.
Two.
Isotopes. They differ in the number of neutrons in the nucleus.
An atom or element that have different masses are known as isotopes.
All erbium ordinarily found in nature is of stable isotopes. Like all other elements, erbium has synthetic radioactive isotopes.
Erbium has 68 electrons.
Element #68 is Erbium. The number of the isotope, of course, is the sum of the protons + neutrons. Checking the Wikipedia article "Isotopes of erbium", it looks as if this isotope doesn't actually exists.
That depends on the isotope, as Argon has three different stable isotopes and many different radioactive isotopes.
Two.
hydrogen plus erbium
Isotopes. They differ in the number of neutrons in the nucleus.
An atom or element that have different masses are known as isotopes.
Many elements have different isotopes: 1) Carbon - Carbon 12, Carbon 14 2) Hydrogen - Protium, Deuterium, Tritium 3) Chlorine - Chlorine 35, Chlorine 37 etc
what are the names of 15 different isotopes
Isotopes have a different number of neutrons.
Protons-68 Electrons-68 Neutrons-About 99