Download Basic Atomic Structure and Chemical Bonding Goals: Understand

Basic Atomic Structure and Chemical Bonding
Goals: Understand and explain basic atomic structure. Be able to determine number of subatomic
particles. Form chemical bonds.
Subatomic Particles
Protons are positively charged
Neutrons have no charge
Electrons are negatively charged
Protons and neutrons are found in the center of the atom (nucleus) and together, make up
nearly all the mass of the atom.
Protons determine the physical qualities of the element
Electrons determine the chemical properties of the element
Determining the number of subatomic particles
In a NEUTRAL atom the number of subatomic particles can be found like this:
The number of protons for an element can be determined by that elements atomic number.
The number of electrons will equal the number of protons
The number of neutrons can be found by subtracting the atomic number from the atomic mass.
Isotopes.
There are many elements that have multiple forms. Being the same element, they will all have
the same number of protons. However, they have differing atomic masses, due to differences in their
number of neutrons.
Determining the number of subatomic particles of an Ion.
Sometimes atoms will become charged, or ionized. This occurs when the number of electrons is
different than the number of protons. To find the number of electrons, you must consider the charge. If
an atom is positively charged, the number of electrons will be less than the number of protons. If it is
negatively charged, the number of electrons will be greater.
Valence Electrons.
While larger elements will have greater numbers of electrons, there are only a few that we
actually care about. The electrons on the very outside of the atom are the ones that we will focus on.
They are the ones involved with chemical bonding, and therefore the most important.
The number of valence (outermost) electrons can be determined by the periodic group to which
the element belongs.
Dot Structures.
Dot structures serve as a visual representation of the valence electrons. When forming dot
structures, remember that no two electrons may be paired until the total number of valence electrons is
greater than four.
Ionic Bonds.
Ionic bonds exist between a metal and a non-metal.
The metal literally and physically “gives” its electrons to the non-metal, which “takes” the
electrons donated by the metal. This results in both becoming ionized, and the bond is formed due to
the opposite charges.
Covalent Bonds.
Covalent bonds are formed by two or more non-metals. Because these elements have no great
desire to give up electrons, they opt instead to “share” valence electrons. It is the sharing of electrons
and the resulting overlapping of electron clouds that holds the elements together.