Fundamentals of Nuclear Chemistry - Gemini Notebook

What is nuclear chemistry?

The study of reactions involving changes in atomic nuclei.

Who discovered natural radioactivity, establishing the foundation of nuclear chemistry?

Antoine Becquerel, followed by extensive studies conducted by Pierre and Marie Curie.

What is radioactivity?

The spontaneous emission of particles and/or electromagnetic radiation by unstable nuclei.

What is nuclear transmutation?

Radioactivity resulting from the bombardment of nuclei by neutrons, protons, or other nuclei, such as $n + {}^{14}\text{N} \rightarrow {}^{14}\text{C} + p$.

How do the energy changes in nuclear reactions compare to those in chemical reactions?

Chemical reactions are accompanied by the absorption or release of relatively small amounts of energy, whereas nuclear reactions involve tremendous amounts of energy.

How do external conditions like temperature, pressure, and catalysts affect nuclear reactions versus chemical reactions?

Chemical reaction rates are affected by temperature, pressure, concentration, and catalysts, whereas nuclear reaction rates normally are not affected by temperature, pressure, or catalysts.

In nuclear notation ${}_Z^A\text{X}$, what do the superscript $A$ and subscript $Z$ represent?

The superscript $A$ is the mass number (protons + neutrons), and the subscript $Z$ is the atomic number or charge (protons).

What are the composition, mass number, and charge of an alpha particle ($\alpha$)?

An alpha particle (${}_2^4\alpha$) is a Helium-4 nucleus containing 2 protons and 2 neutrons, with a mass number of $4$ and a charge of $+2$.

What is a beta particle ($\beta$) and how does it originate in the nucleus?

A beta particle (${}_{-1}^{\phantom{-}0}\beta$) is a high-speed electron with a mass number of $0$ and charge of $-1$, emitted when a neutron converts into a proton and an electron (${}_0^1 n \rightarrow {}_1^1 p + {}_{-1}^{\phantom{-}0}\beta$).

What is a positron ($\beta^+$)?

The antimatter counterpart (antiparticle) of the electron, having the same mass (mass number $0$) and a positive charge ($+1$), designated as ${}_{+1}^{\phantom{+}0}\beta$.

What is a gamma ray ($\gamma$)?

A high-energy photon with zero mass (mass number $0$) and zero charge ($0$).

What are the two fundamental conservation laws required for balancing nuclear equations?

Conservation of Mass Number (total sum of $A$ of reactants equals products) and Conservation of Atomic Number (total sum of $Z$ of reactants equals products).

In the alpha decay equation ${}_{84}^{212}\text{Po} \rightarrow {}_{82}^{208}\text{Pb} + \text{X}$, what is the identity of particle $\text{X}$?

An alpha particle (${}_2^4\alpha$), with mass number $A = 4$ and atomic number $Z = 2$.

In the beta decay equation ${}_{55}^{137}\text{Cs} \rightarrow {}_{56}^{137}\text{Ba} + \text{X}$, what is the identity of particle $\text{X}$?

A beta particle (${}_{-1}^{\phantom{-}0}\beta$), with mass number $A = 0$ and atomic number $Z = -1$.

What is the density of a typical atomic nucleus with radius $r = 5 \times 10^{-3}\,\text{pm}$ ($5 \times 10^{-13}\,\text{cm}$) and mass $1 \times 10^{-22}\,\text{g}$?

$2 \times 10^{14}\,\text{g/cm}^3$.

How does nuclear density compare to Osmium, the densest known element?

Nuclear density is roughly $9 \times 10^{12}$ (9 trillion) times denser than Osmium ($22.6\,\text{g/cm}^3$).

What is the strong nuclear force, over what distance does it act, and how strong is it relative to electrostatic repulsion?

A short-range attractive force between proton-proton, proton-neutron, and neutron-neutron pairs operating over femtometer distances ($10^{-15}\,\text{m}$) that is 137 times stronger than electrostatic repulsion.

What intranuclear condition dictates whether a nucleus is stable or undergoes radioactive decay?

If attractive forces prevail, the nucleus is stable; if electrostatic repulsion outweighs attraction, the nucleus is unstable and undergoes radioactive decay.

What is the neutron-to-proton ($n/p$) ratio for light elements ($Z \le 20$), and why does it increase for heavier elements?

For light elements ($Z \le 20$), stable nuclei have $n/p \approx 1$; as $Z$ increases, $n/p > 1$ because extra neutrons are required to buffer proton-proton electrostatic repulsion.

What are the magic numbers of protons or neutrons that confer exceptional nuclear stability?

2, 8, 20, 50, 82, and 126.

Why is Lead-208 (${}_{82}^{208}\text{Pb}$) classified as a doubly-magic nucleus?

It contains 82 protons and 126 neutrons, both of which are magic numbers.

According to nucleon pairing rules, how many stable isotopes have an even number of protons and an even number of neutrons?

164 stable isotopes.

According to nucleon pairing rules, how many stable isotopes have an odd number of protons and an odd number of neutrons?

4 stable isotopes, which are highly uncommon and mostly unstable.

At what atomic number threshold are all isotopes of an element radioactive?

All isotopes of elements with atomic numbers greater than 83 ($Z > 83$) are radioactive.

Which two elements with atomic numbers lower than 84 have only radioactive isotopes?

Technetium ($Z = 43$) and Promethium ($Z = 61$).