Atoms, Ions, & Isotopes:
A short review and webquest
SWBIC Educational Resources
Activities & Materials
Atoms, Ions, & Isotopes
An Atom is the smallest recognizable part of an element containing protons
(positively charged particles), neutrons (neutral particales), and electrons
(negatively charged particales). Atoms are electrically neutral because
they are composed of an equal number of protons and electrons.
- Periodic Table - an interactive
chart of the elements.
- Table of Atomic
Electronegativity - a periodic table with electronegativities
given for each element.
- Electronegativity and Bonding - an article
describing the relationship between electronegativity and bond
Valence electrons and Bonding - the relationship between
valence electrons and chemical formula.
An ion is an atom that has gained or lost electrons. In non-nuclear chemistry
an atom never gains or loses a proton; only the number of electrons is
The following shows how a hydrogen ion is formed. The image on the left is a
hydrogen atom; therefore containing an equal number of protons and electrons.
The atom on the left has lost its electron; it is now an ion, and not
an atom, because there is no longer an equal number of protons and electrons.
The result is a charge imbalance known as a hydrogen ion.
Now let's look at how a positive ion of beryllium is formed. Below, on the
left, is a neutral atom of beryllium containing four protons and five
neutrons. Circling the nucleus are four electrons. On the right, the atom has
lost two electrons. The resulting ion still has four protons in the nucleus
but contains only two electrons. There are now two more positive than
negative charges, therefore the ion has an overall charge of 2+.
A negative ion is formed in a similar way. Below, on the left, is a image of a
neutral fluorine atom containing nine protons, nine electrons, and ten
neutrons. When fluorine enters into a compound, it picks up an electron from
the atom it bonds with. The resulting ion, called a fluoride ion,
contains ten electrons and nine protons, with an overall charge of 1-.
Ions in the
Sodium-Potassium Pump - how the interplay of these ions control
the movement of muscles.
Ions and your taste buds - how ions regulate taste.
Isotopes are atoms of the same element that contain different numbers of
neutrons and thus have different masses. Below are drawings of the three
naturally occurring isotopes of hydrogen; note that they differ only in the
number of neutrons contained in their nucleus. The isotope in Fig. 1 contains
only one particle in its nucleus: this isotope has a mass of one unit and
is known as normal hydrogen. Fig. 2 shows a rare isotope of hydrogen. Its
nucleus contains two particles (a proton and a neutron) and has a mass of
two units. It is known as heavy hydrogen. Figure 3 depicts an isotope known
as heavy-heavy hydrogen. The nucleus contains three particles (one proton
and two neutrons) and has an overall mass of three units.
What is radioactivity? - a basic primer
on the consequence of isotopes.
isotopes in the Hershey-Chase experiment - how Hershey and Chase used
isotopes in their famous experiment.
Medical uses of isotopes
- different ways in which isotopes are used in the medical field.
Industrial uses of isotopes - several industrial uses of isotopes.
scientific research - how one scientist uses isotopes in her
Developed for SWBIC by John Palmer, Gadsden High School.