Question

Emission of one \(\alpha\) -particle from a nucleus results the loss of two protons and two neutrons from the nucleus. These four particles (two protons and two neutrons) comes out from the nucleus (a) all at a time. (b) one by one, both protons followed by both neutrons. (c) one by one, both neutrons followed by both protons. (d) one by one, protons and neutrons alternatively.

Short answer

(a) all at a time. In alpha decay, an alpha particle, which consists of two protons and two neutrons, is emitted all at once as a unit, not sequentially.

Step-by-step solution

Understanding Alpha Decay

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into a nucleus with a mass number reduced by 4 and an atomic number reduced by 2. An alpha particle is identical to a helium-4 nucleus and consists of two protons and two neutrons bound together.

Analyzing the Emission Process

The alpha particle is emitted as a single unit, which means that the two protons and two neutrons do not come out individually but rather as a cluster that forms the helium-4 nucleus.

Eliminating Incorrect Options

Given that the alpha particle is emitted as a single unit, option (a) 'all at a time' accurately describes this process. Options (b), (c), and (d) imply a sequential emission of protons and neutrons, which is incorrect in the context of alpha decay.

Key concepts

Radioactive Decay

Radioactive decay is a fundamental process in which unstable atomic nuclei release energy in order to gain stability. It's a natural, spontaneous process that occurs in various forms, one of which is alpha decay. Imagine holding a ball on a slope, and because of gravity, the ball wants to roll down to a stable position. In a similar way, certain atomic nuclei are in an unstable (high-energy) state and they 'roll' towards stability by emitting particles and radiation.

There are several types of radioactive decay, such as alpha decay, beta decay, and gamma decay. Each type of decay involves a different set of changes within the atomic nucleus, and leads to the production of different particles or energy. For instance, alpha decay specifically results in the emission of an alpha particle, while beta decay involves electrons or positrons, and gamma decay releases electromagnetic radiation.

Understanding radioactive decay is crucial not only for comprehending nuclear physics but also its practical applications in medical treatment, energy production, and even archaeological dating through techniques like carbon-14 dating.

Atomic Nucleus

The atomic nucleus is the heart of an atom. It's a dense region at the center of an atom where protons and neutrons are tightly bound by the nuclear forces, which are strong interactions far greater than the electromagnetic repulsion between the positively charged protons. It's like a tiny, incredibly crowded party where everyone is sticking together despite some wanting to push away.

The number of protons in the nucleus defines the element. For example, an element with six protons is always carbon, and one with eight protons is oxygen. Neutrons, on the other hand, contribute to the mass of the nucleus without altering its elemental identity. They serve as a sort of glue, helping to stabilize the nucleus by mediating the strong forces and offsetting the repulsion between protons.

However, if a nucleus has too many or too few neutrons for the number of protons it contains, it may be unstable. Such an imbalance can make the nucleus prone to radioactive decay as it seeks a more stable configuration. This leads to the fascinating and complex behavior of radionuclides and their decay paths.

Alpha Particle Emission

Alpha particle emission is an intriguing process where an unstable atomic nucleus releases an alpha particle to find stability. An alpha particle is akin to a tightly-knit group, consisting of two protons and two neutrons, the same as a helium-4 nucleus. This particle is a chunk of nuclear material that's ejected all at once, not gradually or piece by piece.

Diving into the specifics, an alpha particle carries a positive charge due to its protons, and this affects its interactions as it travels away from the parent nucleus. When the expulsion happens, it's a bit like a tiny, high-energy cannonball being shot out of the nucleus. The alpha particle typically has a high kinetic energy but, because it's relatively heavy and positively charged, it doesn't travel very far outside the nucleus before it is absorbed by surrounding materials.

The emission process does not involve the protons and neutrons leaving one by one; they leave as a pre-formed, bound unit. Therefore, when students are confused about how the alpha particles are emitted in nuclear decay processes, it's helpful to visualize the emission as a sudden release of this pre-formed, highly stable group of particles.