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The mass of a mole of
molecules ofa substance is the molecular mass expressed in grams. For example,
an oxygen molecule (O2) has
a molecular mass equivalent to 32.0 grams because each oxygen atom has a
molecular mass of 16.0 grams. (Recall that to obtain the molecular mass, the
atomic masses of all atoms that appear in the formula are added.) If the atomic
masses of the carbon and four hydrogen aoms in methane, CH4, are
added, the total is 16 amu. Therefore, one mole of CH4 has a mass of
16 grams. The mass of a mole of molecules is called the molar mass or gram
molecular weight(GMW). Summary The important information
found in this chapter is summarized below. Characteristics of Atoms
Summary The following terms are
defined: States of matter is a
term which refers to the physical forms in which matter exists; solid, liquid
and gas. Solids are characterized as having both a definite shape and a
definite volume. Liquids have definite volumes but indefinite shapes and are
slightly compressible. Gases are readily compressible and capable of infinite
expansion. Atomic weight is defined
as the weighted average of the masses of all its natural occurring isotopes. Molecular weight will be
the total weight of the individual atoms of a molecule. A mole is Avogadro's
number of any substance. Gram atomic weight is the
mass of a mole of atoms. Gram molecular weight is
the mass of a mole of molecules, (GMW). The components of an atom
are protons, neutrons, and electrons. A proton has a mass of 1.0 amu and a
positive charge (+1). The neutron also has a mass of 1.0 amu but is neutral in
charge. The electron has a mass of .00055 or 1/1835 amu and a negative charge
(-1). An atom is classified
chemically by the number of protons in its nucleus. <%CUT%> THE PERIODIC TABLE All known elements
fall into a pattern when placed in a periodic table, and the position in this
pattern is decided by the element's atomic number. This chapter will discuss
the significance of this fact. EO 1.4 DEFINE the following subdivisions of the
periodic table: a.Periods of the periodic table b.Groups of the periodic table c.Classes of the periodic table EO1.5 Given a periodic table, IDENTIFY the
following subdivisions: a.Periods of the periodic table b.Groups of the periodic table c.Classes of the periodic table EO 1.6 LIST the characteristics that elements in
the same group on the periodic table share. EO 1.7 DEFINE the term valence.
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