HON CHEMISTRY: Happy Friday! Here’s the lesson for today. First, a look at some of the homework from last night, and then onward to chapter 21!
Speaking of – welcome to nuclear chemistry! No, really – I think you’ll be surprised how much nuclear chemistry is already a part of your everyday life. And now you know where E=mc2 came from!!
By the way, when you get a chance, read about the life of Marie Cure – fascinating woman of science with an incredible story!
What is the nuclear mass defect, why does it happen, and what is the equation for it?
The nuclear mass defect is when there is a loss of mass when a nuclide is formed. Ordinarily, this would not be possible, but in nuclear reactions, it occurs because the mass that was lost was converted into nuclear binding energy, which affects the stability of the nuclide. Albert Einstein used this information to create the formula, E=mc^2.
Q: How does knowing the initial amount of nuclear binding energy that is released when a nuclide is formed help scientists know how to split an atom?
A: When scientists split an atom, they have to exert the same amount of energy on the atom that there was nuclear binding energy to overcome the strong forces of the atom and split it. Therefore, knowing the amount of nuclear binding energy of the atom can help them use that same amount of energy to split an atom.
Q: In nuclear binding energy happens mass is lose. That contradicts the law of conversation of mass, so how is that possible.
A: it would not happens but since splitting atoms are not an ordinary chemical reaction it is an exception that mass is lose during nuclear binding energy. That mass is converted into binding energy so that it will be stable.
Q: Since we typically associate radioactive substances as dangerous and harmful to the human body, how are some radioisotopes safe to use in medicine?
A: When a radioisotope comes in contact with a healthy cell, it can create harmful consequences. On the other hand, when a radioisotope comes in contact with an infected cell, it can reverse the infection.
Q- How did Ernest Rutherford know that there was a nucleus in the middle of atoms and it is small.
A- Because most of the positive particles passed through the gold atoms, and only a small amount of them were repelled by the positive particles in the atoms, he was able to conclude that the positive particles were packed tightly together and in the center of the atom.
Q: Why is energy produced during the formation of a nuclide, when energy can’t come from nothing?
A: Mass thought to be lost when a nuclide is formed actually is converted into energy.
Q: Why does the nucleus hold together if protons should repel because of their positive charges?
A: Protons are made of quarks and gluons. The gluons hold the quarks together, and the exchange of gluons between different protons results in the strong nuclear force. The strong nuclear force holds the protons together at very small distances. The gluon can move only very short distances, so the strong nuclear force can only act over distances shorter than the nucleus. The strong nuclear force overcomes the electromagnetic force.
Q: Why is strong nuclear force important to all-known life, and what would happen if it vanished?
A: Strong nuclear force is the force that holds all the nucleons inside the nucleus together to keep it stable, and if that force vanished one day, all atoms would break apart in an instant. Thus, everything would cease to exist, and the universe would be quite mundane.
q: how did marie curie know that there had to be more than one radioactive element in the pitchblende?
a: curie observed 2 different levels of radioactivity in the pitchblende, to which she concluded there was definitely more than one radioactive element. the ore proved to be more radioactive then the uranium, and that led to more experiments discovering the polonium and radium. those elements were the ones that exhibited the different radioactive levels.
Q: Why is the atomic mass for each element on the periodic table not a whole number?
A: It is the weighted average of all the naturally occurring isotopes of an element. Because each element has multiple naturally occurring isotopes that affect this average, its “atomic mass” as seen on the periodic table will never be whole.
Q: Why is it that a nucleus is more stable the higher its binding energy is?
A: The amount of energy needed to split an atom apart is the same amount as the energy released for it to form. Therefore, a nuclide that has high binding energy needs a larger amount of energy to break it apart, and a nuclide that has low binding energy needs a smaller amount of energy to break it apart.
Q: Why is polonium radioactive, but bismuth is not?
A: Bismuth is not radioactive because it has a stable nucleus, whereas polonium does not. As the number of protons in the nucleus increase, the repelling force among the protons becomes greater than the strong nuclear force. In elements beyond bismuth, such as polonium, the repelling force of protons is so intense that no stable nuclides exist since the strong nuclear force cannot overcome this repelling force.
Q: If you were to weigh the parts of an atom of a certain element against the atom itself of the element why wouldn’t they be completely balanced?
A: They wouldn’t be completely balanced because when the atom is formed nuclear binding energy is formed from seemingly nowhere however it has been discovered that the nuclear binding energy formed is a result of the parts of the atom losing some of their mass making the atom offset the balance since it had lost mass from the conversion of mass to energy when it was being formed.
Q: Why is energy gained and mass lost in the formation of a nuclide? Who explained this and how?
A: Albert Einstein explained that the mass lost was converted into nuclear binding energy during the process of forming a nuclide with the equation: E= mc^2. E represents energy, m represents mass, and c represents the speed of light.