As we know, Number of protons = Atomic Number
So,
And, Atomic mass = Number of protons + Number of Neutrons (N)
therefore ~
Number of Neutrons = 19
The atomic mass of the element = 24.309547
<h3>Further explanation</h3>
Given
Isotopes of Mg
Required
The atomic mass
Solution
Atomic mass is the average atomic mass of all its isotopes
Mass atom X = mass isotope 1 . % + mass isotope 2.% ..
The atomic mass of the element(Mg) :
= 23.98504 . 0.7870 + 24.98584 . 0.1013 + 25.98259 . 0.1117
= 18.876226 + 2.531066 + 2.902255
= 24.309547
The group of elements which have the lowest ionization energy are the alkali metals
<span>Potential energy. This energy refers to the energy that is possessed by a physical object by virtue of its relative position with respect to other tangible objects that are in its vicinity. This energy keeps on changing as an object is set in motion.</span>
Answer:
3.125 grams.
Explanation:
- It is known that the decay of a radioactive isotope isotope obeys first order kinetics.
- Half-life time is the time needed for the reactants to be in its half concentration.
- If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
∵ Thulium-167 has a half life of 9.0 days.
∴ The time is needed to calculate the grams are left after (36.0 days) represents (36.0 days / 9.0 days) = 4.0 half-lives.
50.0 grams → (first half life) 25.0 grams → (second half life) 12.5 grams → (third half life) 6.25 grams → (fourth half life) 3.125 grams.
So, the grams are left after 36.0 days = 3.125 grams.