Atoms, Molecules, and Ions
This chapter develops the concepts of atoms, molecules, and ions - the building blocks of all
Upon completion of Chapter 2, students should be able to:
List the hypotheses of Dalton’s atomic theory.
Distinguish between the law of definite proportions and the law of multiple proportions.
Explain how Dalton’s fourth hypothesis is another way of stating the law of
conservation of mass.
Describe how electrons were discovered and how Millikan’s oil drop experiment
determined the charge of the electron.
Predict the path of alpha particles, beta particles, and gamma rays as they pass between
two oppositely charged electrical plates.
Describe how Rutherford’s experiment concluded that atoms are mostly empty space
with very small central cores, known as nuclei.
Predict the path of protons, electrons, and neutrons as they pass between oppositely
charged electrical plates.
Indicate the number of electrons, protons, and neutrons in atoms and ions.
Give examples of isotopes.
Write the names for the three isotopes of hydrogen.
Identify whether an element is a metal, nonmetal, or metalloid.
12) Classify elements as alkali metals, alkaline earth metals, or noble gases.
13) List several examples of diatomic molecules.
14) Classify ions in terms of momatomic ions, polyatomic ions, cations, and anions.
Describe the differences between molecular and empirical formulas.
Give examples of correct formulas for ionic compounds.
17) Name common ionic compounds, molecular compounds, binary acids, oxoacids, bases,
and hydrates given their respective chemical formulas.
18) Predict the chemical formulas of common ionic compounds, molecular compounds,
binary acids, oxoacids, bases, and hydrates given their respective names.
The Atomic Theory
John Dalton’s atomic theory is the basis for the modern era of chemistry.
can be summarized in the following way:
Elements are composed of extremely small particles called atoms.
All atoms of a given element are identical, having the same size, mass, and chemical
properties. The atoms of one element are different from atoms of all other elements.
(Lego blocks can be used as an example).
Compounds are composed of atoms of more than one element.
In any compound, the
ratio of the numbers of atoms of any two elements present is either an integer or a