Chemistry I Chapter 3 Outline
ATOMS: THE BUILDING BLOCKS OF MATTER
For graded assessments, you will need to be familiar with the following
terms:
Law of conservation of mass, law of definite proportions, law of multiple
proportions, atom, nuclear forces, atomic number, isotope, mass number,
nuclide, atomic mass unit (amu), average atomic mass, mole, Avogadro’s
number, molar mass.
I. THE ATOM: FROM PHILOSOPHICAL IDEA TO SCIENTIFIC THEORY
A. Foundations of Atomic Theory: Be familiar with names that are
attributed to theorizing about the smallest, indivisible part of matter (the
atom); names from ancient Greece as early as 400b.c. such as
Democritus and Aristotle. (pg. 67)
i. Which of the two above philosophers first described
the atom as “indivisible”?
____________________________________________
ii. Which of the two above mentioned philosophers did not believe
in the atom but instead believed that all matter was continuous?
____________________________________________
(STANDARD: CLE 3221.1.1)
B. Dalton’s Atomic Theory: Be familiar with Dalton’s 5 statements that
theorized the characteristics of all atoms. (pg. 68)
i. All matter is composed of
___________________________________ called atoms.
ii. Atoms of a given element are identical in ___________,
_________, and other ________________; atoms of different
elements differ in _____________, _______________, and
______________________.
iii. Atoms cannot be _____________, _____________, or
____________________.
Iv. Atoms of different elements combine in simple
______________________________________ to form
compounds.
v. In chemical reactions, atoms are ________________,
____________, or _____________.
**NOTE: the purpose of this exercise is to practice associating
these ideas with the historical scientist John Dalton. There is, in
fact, a unit of measurement named after him in the sub discipline,
biochemistry. Dalton’s atomic theory will come up many times
throughout your academic career in the sciences and as such, it is
also a standard that his theory work is familiar.
vi. According to Dalton’s theory, the law of conservation of mass
is explained in that chemical reactions involve merely the
combination, separation, or rearrangement of atoms and that during
these processes atoms are not subdivided, created, or destroyed.
Refer to pg. 69, figure 2. Which example illustrates this law?
_________________________________
Which of the two illustrates the law of definite proportions?
__________________________________
Define the law of definite proportions.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________.
C. Modern Atomic Theory: Understand that although these historical
scientific pioneers contributed greatly to what we understand about
science today, their ideas, particularly Dalton’s, have been modified
according to more contemporary scientific data.
i. One important concept that remains unchanged is that
ii. Another concept that remains unchanged is that
_____________________________________________________
_____________________________________________________
_____________________________________________________
(STANDARD CLE 3221.1.1 & CLE 3221.3.4)
II. THE STRUCTORE OF THE ATOM (pg. 72 – 76)
A. Electron Discovery: What are the two regions that all atoms have?
_______________________________________________________.
i. The nucleus consists of the subatomic particles ___________
and ______________.
ii. ____________ are located outside the nucleus, are in constant
orbital motion about the nucleus, and are involved in forming
chemical bonds.
iii. Proton, neutrons and electrons are called
______________________.
iv. What is a cathode ray composed of?
____________________________________________
____________________________________________
v. Ernest Rutherford used what to help substantiate the
composition of an
atom?__________________________________________
vi. According to Rutherford et. al., the nucleus of an atom is
incredibly __________________; this conclusion was based on the
fact that the alpha particles that bombarded the gold foil
______________________.
vii. Please review Rutherford et. al., experiment illustrated on pg.
74, figure 6. Be able to explain how this group of researchers were
able to theorize on the structure of an atom and how their theories
contribute to contemporary science and our understanding of the
atomic structure – the fact that an atom is composed of an
incredibly dense nucleus composed of protons and neutrons with a
‘cloud’ of electrons in constant orbital motion about this positively
charged nucleus.
B. Composition of the Atomic Nucleus: The proton’s positive charge is
equal in magnitude to the negative charge of an electron. Atoms are
electrically neutral because they contain equal numbers of protons and
electrons. A neutron is ________________________.
i. In terms of mass, list the greatest to the smallest of the
subatomic particles. _________________________________
ii. The number of protons determines that atom’s _____________.
iii. Define nuclear forces. _______________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________.
C. The Sizes of Atoms: Because atomic radii are so small, they are
expressed using what unit? _______________________________.
Express the conversion factor for 1pm to the meter. ________________
__________________________________________________________.
(STANDARDS CLE 3221.1.1 & CLE 3221.Inq.2 – 6)
III. COUNTING ATOMS (pg. 77 – 87)
A. Atomic Number: Define the atomic number as it appears on a periodic
table of elements.
__________________________________________________________
__________________________________________________________.
B. Isotopes: are atoms of the same _______________ that have different
_____________. They have a different number of ___________ than
______________; this is why they have a different mass from a ground
state elemental atom.
C. Mass Number: the mass number of an element is the total number of
protons and neutrons that make up the nucleus of an isotope or atom.
i.
Review table 2 on page 78 for an example of the difference
between the varying isotopes of the hydrogen atom.
D. Designating Isotopes: Review this section and understand how
isotopes are expressed. If you have questions, please let me know. For
example, Uranium – 235 has a mass number of 235 which is the protons +
neutrons but Uranium only has 92 protons, therefore it will have 143
neutrons. You will need to refer to your periodic table to confirm this.
E. Relative Atomic Masses: Know that one atomic mass unit, or 1 amu, is
1/12 of the mass of a carbon-12 atom.
i. Although isotopes have different masses, they do not differ
significantly in their ______________________. (pg. 81)
F. Average Atomic Masses of Elements: Define average atomic mass.
________________________________________________________
________________________________________________________
i. Understand relative abundance of elemental species as indicated
on pages 80 – 82.
G. Relating Mass to Numbers of Atoms: Define the mole. ___________
__________________________________________________________
__________________________________________________________.
H. What is Avogadro’s Number? ________________________________
___________________________________________________________
___________________________________________________________
I. Molar mass is defined as the mass of one mole of pure substance.
J. Practice the sample problems on pages 84 – 87. You will need to
know how to convert grams to moles, moles to grams, moles to atoms,
atoms to moles and etc….
(STANDARD CLE.3221.MATH.2)