The thorium- 232 radioactive decay series, beginning with...

Key Concepts

Nuclear Equation Balancing

When writing equations for decay series, it is essential to properly balance the nuclear equations to reflect the accurate changes in the atomic and mass numbers. This involves accounting for the emitted particles such as alpha particles in alpha decay and beta particles in beta decay, thus ensuring that all conservation laws are met.

Conservation Laws in Nuclear Reactions

Nuclear equations must adhere to the conservation of both mass number (total number of nucleons) and atomic number (number of protons). This principle ensures that the sum of the numbers on the reactant side equals that on the product side in every step of a decay series.

Beta Decay

Beta decay is a nuclear process in which a neutron is converted into a proton (or vice versa) with the emission of a beta particle (an electron or a positron) and an associated neutrino. In beta-minus decay, the atomic number increases by one while the mass number remains unchanged, making it a key mechanism for altering the identity of the nucleus in decay chains.

Alpha Decay

Alpha decay is a type of radioactive decay in which an unstable nucleus loses energy by emitting an alpha particle, which consists of two protons and two neutrons. This emission results in the decrease of the atomic number by 2 and the mass number by 4, and it is a crucial process in many decay series.

Radioactive Decay Series

This refers to the sequential process in which an unstable nucleus undergoes multiple decay events, transforming through a series of intermediate isotopes until reaching a stable nuclide. Each step in the series follows a specific decay mode, and the complete series can be represented by a set of nuclear equations that indicate the transformation from the parent to the daughter isotope.

Transcript

00:01 The thorium 232, radioactive decay series, beginning with thorium 232 with atomic number of 90, and ending with lead, 208.

00:10 Of course, in the following sequence, alpha decay, followed by 2 beta decay, and then 4 alpha decay, 2 beta decay, and 1 alpha decay.

00:22 So we need to write an equation for each step in this series.

00:26 So, of course, we need to start first with the alpha decay of thorium.

00:30 232.

00:32 Take note that in alpha decay, an alpha particle is produced, which is represented by alpha symbol with atomic number of 2 and mass number of 4.

00:43 So let me write that down first.

00:45 Thorium 232 with a mass number of 232 and atomic number of 90.

00:51 It's producing an alpha particle with atomic number of 2 and mass number of 4.

01:00 So to balance this equation, we need to add an element, say, x.

01:05 And then for the mass number, we simply subtract 4 from 2, 3, 2 .2, so we'll get 288.

01:13 And then for the atomic number, let's subtract 2 from 90, then we'll get 88.

01:19 Then to find out the identity of x, we use the periodic table.

01:26 And based on the periodic table, the element with atomic number of 88 is radium represented as ra.

01:37 Okay, let me center this one.

01:42 So we have more space.

01:45 And then for the beta decay, the radium 288 will undergo beta decay.

01:55 So take note that in beta decay, beta particle represented as beta with atomic number of negative.

02:01 1 and mass number of 0 is 3d.

02:03 So let me write it down.

02:04 So we have a radium 228 -28 -i -mean and atomic number of 88.

02:12 So it produces alpha, i mean beta particle during beta -d -k...

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