Question

What change in atomic number occurs when a nucleus emits an alpha particle? A beta particle?

Short answer

Alpha emission decreases atomic number by 2; beta emission increases it by 1.

Step-by-step solution

Understanding Alpha Particle Emission

An alpha particle is composed of 2 protons and 2 neutrons, resembling a helium nucleus. When a nucleus emits an alpha particle, it loses these 2 protons and 2 neutrons.

Calculating Change in Atomic Number for Alpha Emission

Since 2 protons are removed from the nucleus during alpha emission, the atomic number decreases by 2. The new atomic number is the original atomic number minus 2.

Understanding Beta Particle Emission

A beta particle is an electron emitted from a nucleus when a neutron decays into a proton. This process increases the number of protons in the nucleus.

Calculating Change in Atomic Number for Beta Emission

When a beta particle is emitted, the atomic number of the nucleus increases by 1 because a neutron transforms into an additional proton.

Key concepts

Alpha Particle Emission

Alpha particle emission is an interesting and important concept in nuclear physics. An alpha particle itself is quite unique as it is made up of 2 protons and 2 neutrons. This setup is similar to a helium nucleus, which is why alpha particles can essentially be seen as tiny helium nuclei. When a nucleus ejects an alpha particle, it loses those 2 protons and 2 neutrons.
This means the element undergoing this type of nuclear decay will experience a decrease in its atomic number by 2. This action effectively transforms the element into a different one, as its defining characteristic, the atomic number, changes. To put it simply:

• Original atomic number: X
• After alpha emission: Atomic number becomes X - 2

Thus, alpha particle emission not only shifts the identity of the element but also impacts the atomic mass of the nucleus, decreasing it by about 4 atomic mass units.

Beta Particle Emission

Beta particle emission offers a different twist to nuclear decay, because it involves the transformation of a neutron into a proton. When this transformation occurs, the neutron in the nucleus converts into a proton and an electron. It's this electron that we call a beta particle. This beta particle is ejected from the nucleus and leaves behind an additional proton.
One might wonder, what impact does this have on the atomic number? Well, since there's one more proton present in the nucleus, the atomic number increases by 1. In this case:

• Original atomic number: Y
• After beta emission: Atomic number becomes Y + 1

This change does not affect the atomic mass significantly since the mass of an electron is negligible. However, the transformation results in the element becoming a different element in the periodic table due to this change in atomic number.

Nuclear Decay

Nuclear decay involves the transformation of an unstable atomic nucleus into a more stable one through various processes, such as alpha and beta emissions. At its core, nuclear decay is a natural process that alters elements and compounds over time, playing a key role in radioactive decay. Each type of nuclear decay affects the nucleus's composition differently.
For alpha particle emission:

• The nucleus loses 2 protons and 2 neutrons.
• Atomic number decreases by 2.
• Atomic mass decreases by approximately 4.

Meanwhile, beta particle emission has another effect:

• The nucleus loses a neutron but gains a proton.
• Atomic number increases by 1.
• The atomic mass remains nearly unchanged.

Understanding nuclear decay helps us in various fields such as medicine, where we use certain radioactive isotopes for diagnostic purposes, and in energy production, where it’s the backbone of nuclear reactors.