Name: ___________________________________ Date: _______________________
Active Learning Exercise A: Atoms, Chemical Bonding, and Molecules
Performance Objectives:
1. Given a description or definition, students will be able to correctly identify the states
of matter (solid, liquid, gas), elements, compounds, molecules, ions, cations, anions,
salts, and isotopes.
2. Given a periodic table of the elements, and a series of problems that deal with the
atom, the student will be able to correctly apply the following principles:
a. Protons, which have a positive charge, and neutrons, which have are neutral charge
each have an atomic mass of 1 and are located in the nucleus of the atom.
b. Electrons are negatively charged, have a mass that is about 1/2000th that of a proton
or neutron, and are located in the electron cloud outside of the nucleus.
c. The atomic number of an element refers to the number of protons in its nucleus. The
atomic number of each element identifies the element. The number of neutrons of any
element can vary.
d. In an electrically neutral atom the number of protons is equal to the number of
electrons.
e. The sum of the number of protons and the number of neutrons in the nucleus of an
atom is equivalent to the atomic mass unit (AMU).
f. Electrons are located in distinct energy levels or shells, in which the number of
electrons in each shell is fixed at 2-8-8 for the first 3 rows of the periodic table. The
number of electrons in the outermost energy level (shell) of an element determines its
chemical reactivity. (Figure 2.6 of the text.)
g. The measure of the pull of the nucleus of an atom on the electrons in the outermost
energy level is called electronegativity, which is determined by the number of electrons
in the outer energy level, and the distance of these electrons from the nucleus of the atom.
3. Given a chemical equation, the student will be able to identify the products and
reactants.
4. Given the structural formula or a description of a compound, the student will be able
to describe bonding between atoms as ionic, covalent, polar covalent, and hydrogen.
Use the Periodic Table of the Elements (Figure 2.5 and Appendix 2 of the text) to
obtain information about particular atoms and molecules, complete this as a home
assignment in critical thinking, pages 17 through 20:
Whether we want to admit it or not, our life is tied up in chemistry. Hence, in order to
understand biology, we also need to have a basic understanding of chemical structure of
living things. Although there are over 112 elements, 92 of which are naturally occurring,
only 6 (hydrogen, carbon, nitrogen, oxygen, phosphorus, and sulfur) make up the bulk of
biological compounds. A few ions, such as potassium, calcium, sodium, and chlorine are
important in biological systems, and a number of elements, such as copper, magnesium,
and iron, are present in small or trace quantities.
Major Concepts: Complete the Table below for the 3 major subatomic particles.
Atomic Structure: Particles Found in an Atom
Name
Mass
Location
Charge
Proton
Neutron
Electron
What is meant by the octet (8) rule (what pattern do we find for the outer energy levels
of electrons) for energy levels of electrons?
Describe the maximum number of electrons that can be found in each of the following
energy levels of the atom, which are represented by the rows of the Periodic Table
(Number of electrons present in each orbital).
Row 1, Energy level 1
Row 2, Energy level 2
Row 3, Energy level 3
Describe what is meant by each of the following:
An element is
An isotope of an element is
A compound is
A molecule is
Describe the 2 ways in which the elements are ordered on the periodic table of the
elements.
Rows: In order of increasing numbers of _______________ (subatomic particle).
Columns: In order of electrons in each _____________________________.
Isotopes:
Look at the element carbon (symbol C) on the periodic table.
What is the atomic number of carbon?
Why is the atomic number always a whole number?
What is the atomic mass of carbon?
Why is the atomic mass usually not a whole number?
How many protons does each carbon atom have?
How many electrons does pure carbon, such as found in your pencil point have?
How many energy levels do the electrons of carbon occupy?
How many neutrons are found in the most common form of carbon, carbon-12?
Carbon has 2 other major isotopes: Carbon –13 and Carbon –14. How many protons
does each of these isotopes have? How many neutrons does each have? Complete the
chart shown here.
Isotope
Number of Protons
Number of Neutrons
Carbon 12
Carbon –13
Carbon –14
Some isotopes of the elements break down (decay), and give off particles from the
nucleus of the atom. In the case of carbon, carbon-14 is radioactive and gives off beta ()
particles (high energy electrons from the nucleus from the breakdown of a neutron).
When this happens, the number of protons changes to 7, and the remaining number of
neutrons is also 7.
What element has 7 protons? ________________________
In this decay process an atom of carbon has become an atom of __________________.
Scientists can measure these radioactive  particles with an instrument known as a Geiger
counter.
The Bonds between Atoms, the Basis of Chemical Changes
Complete the Chart that Follows
Type of Bonding
Condition of
Electrons
Description of the
Bond and Its
Strength
Examples of the
Bonding
Ions are formed
(atoms that have
extra electrons or
fewer electrons)
Strong bond
between equally
electronegative
atoms that share
electrons
Polar covalent
Between water
molecules with each
other and between H
in OH and NH
groups and other O
and N groups