Answer:
<span>2813Al</span>
Explanation:
You know that alpha decay takes place when a α-particle is being ejected from the nucleus of a radioactive isotope.An
<span>α-particle</span> is simply the nucleus of a helium-4 atom. A helium-4 atom has a total of two protons and two neutrons in its nucleus, and two electrons surrounding that nucleus.
In that case, if a <span>α-particle</span> is the nucleus of a helium-4 atom, then it must have a mass number equal to 4, since it has two protons and two neutrons, and a net charge of <span>(2+)</span> since it no longer has the two electrons that the helium-4 atom has.
So, you know that an unknown radioactive isotope decays via alpha decay to yield a sodium-24 nucleus.
A sodium-24 nucleus contains 11 protons and 13 neutrons. This means that you can write
<span><span>AZ</span>X→<span>2411</span>Na+<span>42</span>α</span>
Here A and Z represent the unknown element's mass number and atomic number, respectively.
So, if you take into account the fact that mass number and atomic number must be conserved in a nuclear reaction, you can say that
<span>A=24+4 </span> and <span> Z=11+2</span>
The unknown isotope will thus have
<span>{<span><span>A=28</span><span>Z=13</span></span></span>
A quick look at the periodic table will show you that the element that has 13 protons in its nucleus is aluminum, Al. This means that you're dealing with aluminum-28, an isotope of aluminum that has 15 neutrons in its nucleus.
The complete nuclear equation will be
<span><span>2813</span>Al→<span>2411</span>Na+<span>42</span><span>α
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