First 182 words of the document:
Electrons are the negatively charged particles of atoms.
Together, all of the electrons of an atom create a negative
charge that balances the positive charge of the protons in
the atomic nucleus.
Electrons are extremely small compared to all of the other
parts of the atom. The mass of an electron is almost 1,000
times smaller than the mass of a proton.
Electrons are found in shells that surround the nucleus of
an atom. These shells change depending on how many
electrons an element has. The higher the atomic number,
the more shells and electrons an atom will have.
Rather than drawing the shells, the electronic structure is
often written out. For example, the electronic structure of
carbon atoms is 2, 4 which means there are two electrons
in the first shell, and four in the second. The electronic
structure of aluminium atoms is 2, 8, 3 which means that
there are two electrons in the first shell, eight in the
second and three in the third.