Jump to content

Atoms and molecules


Chuck

Recommended Posts

Are molecules inside the atom?Does that mean that the electrons and protons are outside the atom?I don't know a lot about chemistry but I know that the protons are in the nucleus.Can someone explain to me how a proton is inside a molecule?

Link to comment
Share on other sites

Substances (AKA matter) can come in three forms

Elements

The smallest particles of these are called atoms and cannot be broken down into smaller particles of substance.
The particles of each element are chenically the same as each other but different from the particles of any other element.
There are around 150 elements known.

Compounds.

Two or more atoms of the same or different elements can combine chemically, which means they act as one unit to form molecules.
These are called compund substances or just compounds.
The molecules are thus the smallest particle of compound substances.
All the molecules of a given compound have the same combination of atoms.

 

Mixtures are just what is implied.
A collection of molecules of different compounds and/or elements that are not chemically bound together.

 

Does this help?

Link to comment
Share on other sites

Molecules are made of atoms.

Atom is made of nucleus and electrons.

How many electrons atom can have is defined by number of protons. (aka "atomic number Z")

Sometimes they have smaller number of electrons than protons, or more electrons than protons, and in such case we call them ions. Positive ions (positively charged) and negative ions (negatively charged), depending on sum of number of protons minus number of electrons.

Electrons occupy shells and sub-shells, in specific configuration.

Atom of the same element can have different quantity of neutrons. They're called isotopes.

There is known 118 elements and 3142 isotopes (majority of them are unstable and decay very fast).

 

Nucleus can be destroyed, and free protons and free neutrons, are released. To do it, there is needed external source of energy. Bound proton(s)-neutron(s) of stable isotope has smaller mass-energy than free protons and free neutrons alone. Energy needed to make the all protons and neutrons free from given isotope is called nuclear binding energy.

Nucleus can decay by itself, if it has more mass-energy than decay products (aka "daughter isotopes") such decay would make. It's called radioactive isotope and process radioactivity.

Atom can be ionized. i.e. electron(s) ejected from nucleus. To do it, there is needed external source of energy. Bound nucleus with electrons has smaller mass-energy than free nucleus and free electrons. Valence electrons have the smallest energy required to eject them. Ionization can be caused by photons (aka "light"). If it's done typically with metallic metal, it's called photoelectric effect.

Ionization of atom requires significantly less energy than destruction of nucleus.

e.g. to ionize Hydrogen there is needed 13.6 eV, but to destroy Deuterium nucleus there is needed 2.22 MeV (that's 2.22*10^6 / 13.6 = ~163 thousands more energy)

Energy for ionization, or destruction of nucleus, can be delivered by highly accelerated particles i.e. electrons, protons, neutrons, alpha etc. or by photons (aka "light"), or neutrinos. They must exceed threshold required to destroy nucleus or reaction won't happen.

If highly accelerated particle or photon ejects one of inner electrons, one of outer electrons release photon, and replaces it, and perhaps one of other outer electrons replaces it, and so on. Such cascade effect, releasing many photons. Sometimes they are so strong that they emit light visible by naked human eye. It's called radioluminescence.

Edited by Sensei
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.