Why has the rule about atoms not ever being able to be created or destroyed been modified?

Answer 1

It was once said that matter can neither be created nor destroyed, just changed. But things have changed.

Atoms of helium are created from protons (hydrogen nuclei) They get squashed together to form helium and give off a huge amount of energy that we call an H-bomb blast.

Likewise nuclear processes can take atoms apart.

Einstein showed that matter and energy are convertible with E=mc2 . First we need to clarify things.

The rule that atoms can not be created or destroyed applies only to chemical reactions. This is because such reactions are very low energy reactions. Even the highest energy chemical reactions, high explosive detonations, only rearrange atoms by changing valence band electron bonds. This only involves a small number of electrons in the outer shell.

There are much higher energy reactions that can actually strip all the electrons from an atom. These reactions destroy all chemical properties of the atoms, creating what is called a charged plasma. Man made plasmas are usually formed by running very high electrical currents through a gas. Lightning is a natural plasma created by electricity. Most of the sun, solar flares, and the solar wind are other examples of plasma.

There are even higher energy reactions that destroy the atoms and create totally different atoms. These are nuclear reactions, and are called that because they modify the tiny nucleus at the center of the atom. There are several different kinds of nuclear reactions:

• decay
  • alpha - ejection of a fully ionized helium nucleus, called an alpha particle
  • beta - ejection of an electron or positron, called a beta particle, and the conversion of a neutron to a proton or a proton to a neutron respectively
  • gamma - ejection of a very high energy photon, called a gamma ray
• capture
  • beta - reverse of beta decay
  • K - similar to beta capture of an electron, but the electron came from the atom's own innermost shell (the K shell) instead of from outside the atom
  • neutron - a neutron is added to the nucleus. this usually triggers one or more decays, but in certain very heavy unstable isotopes triggers fission
• fission
  • spontaneous - this can be considered as similar to decay, but the nucleus happens to be so unstable that instead of ejecting small particles as in decay the nucleus splits into several parts (most commonly two parts)
  • chain reaction - splitting of an atom triggered by neutron capture. it becomes a chain reaction because each fission (spontaneous or chain reaction) ejects several neutrons each of which can trigger more fissions
• fusion
  • stellar - this is a series of fusion reactions triggered by gravitational heating from the collapse of the gas making up the star. young stars burn H-H through several steps to make He, older stars burn He-He-He to make C, and so on until the star dies after burning all its fuel making Ni and Fe
  • D-D - a fusion reaction that directly produces He, used by some nuclear weapon designs
  • D-T - a fusion reaction that directly produces He and a neutron, used by almost all fusion type nuclear weapon designs. dry lithium deuteride fueled designs convert the lithium to tritium by using fission neutrons. of the "hot fusion" reactions this is the easiest to ignite as it requires the lowest temperature
  • T-T- a fusion reaction that directly produces He and two neutrons, used by some nuclear weapon designs
  • muon catalyzed cold fusion - the only known fusion reaction that can actually occur and be sustained at room temperature. it operates by replacing the electrons in ordinary hydrogen atoms with muons. muons are particles identical to electrons except they weigh 200 times as much, which causes the orbitals to be 1/200th the size of normal electron orbitals. this allows hydrogen atoms to approach close enough at room temperature to fuse.
  • etc.

The old pre-relativity conservation rules:

• Matter can neither be created or destroyed.
• Energy can neither be created or destroyed.

Are replaced with the new post-relativity conservation rule:

• Mass-Energy can neither be created or destroyed, just converted back and forth.

Answer 2

The rule about atoms not being able to be created or destroyed is still valid. However, in nuclear reactions, atoms can be transformed into different elements or isotopes through processes like fission or fusion. This does not violate the conservation of atoms, as the total number of atoms remains constant.