ENERGY #3: Nuclear B

This occurs when a large, unstable nucleus releases 2 protons and 2 electrons (a He atom). A new, lighter element also results. Notice the proton number of the daughter decreases by 2 and the mass number decreases by 4.

*this is what type of radiation is used in smoke alarms. Because the alpha particle is easily stopped by skin and paper, this is NOT as dangerous unless it is ingested or enters the body in which case it can damage tissue and DNA

to figure it out, notice that the mass # (A)decreases by 4 and the proton # (Z) decreases by 2. This is valid for all alpha decay examples

In Beta Decay an unstable nucleus undergoes a change where within the nucleus a neutron changes into an electron and a proton.

As a result, the daughter element has a proton number increase of 1, and the mass number does NOT change.

Beta particles are more penetrating than alpha particles, but are less damaging to living tissue and DNA because the ionizations they produce are more widely spaced. Skin, clothes or aluminum can stop them.

This is because the nucleus GAINED a proton and so the atomic # (proton number or Z) increased by 1.......the mass # (A) stays the same because although it lost a neutron it gained a proton.

A proton in the nucleus breaks down. It leaves behind a neutron and emits a "positron" (an electron with a positive charge).

The mass# (A) of the daughter element stays the same but the atomic # (Z) is reduced by one.

The daughter element has a decrease in atomic # only.

Notice Beta minus is what we call "beta decay" and that Beta plus is what we call "Positron emission"

Study the pictures so you can differentiate

Notice the beta particle (- electron) is on the reactant side of the equation. This means that an atom absorbed an electron. The electron is taken into the nucleus and merges with a proton resulting in a neutron.

As such, the daughter element has an atomic #(Z) that is reduced by 1 but the mass # (A) stays the same

In gamma decay, the parent element is 'excited'. The only thing that occurs is that the excited parent element releases a burst of energy in the form of a gamma ray. There is no change to the atomic # or the mass #.

Gamma rays are a radiation hazard for the entire body. They can easily penetrate barriers - Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them. Gamma rays can pass completely through the human body; as they pass through, they can cause ionizations that damage tissue and DNA.

In gamma radiation, the parent element is 'excited' and has unstable energy. The energy (gamma photon) is released. No change in atomic # or mass # occurs.

This occurs when a neutron strikes a heavy nucleus. The nucleus breaks into daughter nuclei and in the process releases neutrons and energy (in the picture the energy is quantified as 200 MeV). The Law of Conservation still applies- protons, and neutrons must equal on both sides of the nuclear equation

Notice that on the reactant slide the 'incoming' neutron is not displayed**** but you must count it. Therefore, add 1+235= 236 for a mass # on the reactant side. On the product side--> 90+143+3 = 236

Sometimes, elements go through many types of decay until they are "stable".

An atom can experience more than ONE type of decay (alpha plus gamma, for example