The formula for determination of atomic mass given the mass of isotopes and relative abundance is:
Ar = ∑(mass * abundance) / 100
Ar = (68.92558 * 60.108 + 70.92470 * 39.892) / 100
Ar = 69.72306
The atomic mass of gallium is 69.72306 amu
Answer:
they are composed of water
B) A chemical change because the nail reacts with water/oxygen to create rust (a type of oxide)
Answer:
protons
Explanation:
An element, by definition, always has the same number of protons. Sodium, element 11, has 11 protons. Anything with 11 protons is a sodium atom, regardless of the number of neutrons, electrons, or politicians.
