There are two types of beta decay, and they are beta plus (beta +) decay and beta minus (beta -) decay. A post already exists on beta decay, and a link to that related question can be found below.
Radium-226 does not decay by beta decay. It decays by alpha decay to radon-222.
gamma decay beta decay alpha decay
beta
This does not happen in a single decay event. It requires two separate decay events.
Thorium 234: Beta decay. Atomic number increases by 1.
Beta decay is a property of atoms not molecules.
Radioactive decay; beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted
There is a difference between beta emitters and beta particles. In situations where an atomic nucleus exhibits nuclear instability due to too many neutrons for the number of protons or vice versa, that nucleus may undergo beta decay. It the decay event occurs, that atom is considered a beta emitter. The emitted particle is the beta particle. That's the difference. (There are two different beta particles, so check the articles on beta decay to get the scoop.)
It does not usually involve the atom's electrons, except for a type of decay called K capture. But the beta particles ejected in what is called beta decay are either electrons or positrons.
because the total enegy of the decay is carried by beta particle and the nutrino.
The alpha particle is emitted in alpha decay, and that means you won't see it appear in beta decay. In beta decay, you'll get either an electron or a positron emitted from the nucleus. A link to the related question here can be found below. "What is beta decay?" is already posted and answered.