<h3>Explanation</h3>
Astatine has atomic number 85. "217" is the mass number of this isotope of At.
The mass number of an atom decreases by 4 as it undergoes alpha decay. Its atomic number decreases by 2. It emits an <em>alpha particle</em>, which is a helium-4 nucleus, in this process. The alpha particle has mass number 4 and atomic number 2.
The <em>daughter</em> nucleus has mass number 217 - 4 = 213 and atomic number 85 - 2 = 83. The atomic number of 83 corresponds to bismuth. Therefore the daughter nucleus is an atom of bismuth-213.
By convention, write the mass number A on the top-left corner of an element. Write its atomic number Z on the bottom-left corner. Note that A is always greater than Z for an isotope.
Answer:
Layer 8 is older than layer 1
Explanation:
Answer:
B.109.5
Explanation:
Bond angle :This is the angle between the two bonds present in the atoms or molecule.
Sulphur difluoride(SF2) has a bond angle of 109.5 degrees.
The Na and CO3^2- ions. They are the same on both sides of the equation, so you ignore them and cancel them out.
Answer:
c a reaction that requires energy
Explanation:
because it's moving kind of like a human is being more spontaneous by running and or movement it just sounds spontaneous if you think about energy and if you think about the way it works or away human being moved it's hard to explain but it just makes sense why would it be because it's more ordered that one is definitely the one that don't make sense I just don't think it has nothing to do with what it's trying to ask you this answer just makes sense and has a better understanding