Download Reading the Periodic Table

Reading the Periodic Table
Look at the periodic table of the elements and answer the following questions:
Background
1. Each element is identified by an abbreviation (H = hydrogen, Li = lithium, Na =
sodium, K = potassium and so on - see the page following the table for a complete list).
Find these elements in the table and identify the group to which each belongs. Groups
are designated by a Roman numeral at the top of each column.
Table 2. Group Identification
Atom
Group
hydrogen
lithium
sodium
potassium
2. Elements in each group have common structural and functional properties. For
example, the elements in Group IA each have one electron in the outer shell of their
atoms and are thus highly reactive. They tend to lose this electron in chemical reactions
and to become ions with a single positive charge (e.g., H+, Na+, K+). Atoms in Group
IIA each have two electrons in their outer orbit which are also easily given up to form
ions. What is the charge on these ions? _____________ How would you write the
abbreviations for calcium and magnesium ions?
3. In the periodic table that follows, the number of protons (and in most cases, also of
electrons and neutrons) is designated by the number in the lower left corner of each box
in the periodic table (e.g., H has 1, Li has 3, and Na has 11 protons). This is the atomic
number of the element. What is the atomic number of:
phosphorus (P)? _____________
sulfur (S)?
_____________
4. As noted previously, each neutron and proton has a mass of one, while the weight of
each electron is infinitesimal (close to zero). Thus, helium (He ) has an atomic number of
2, meaning it generally contains 2 protons, 2 electrons, and 2 neutrons. Helium has an
atomic weight of 4.003, as shown at the top of the box. What is the atomic weight of:
carbon (C) _____________
nitrogen _____________
oxygen
_____________
5. Elements are arranged in the periodic table from left to right and top to bottom in order
of increasing mass. The table starts with hydrogen (with an atomic number of one) and
goes to unnilennium (with an atomic number of 109). There is an element for each
atomic number in between, except for 108 which has not yet been observed. What
element has an atomic number of 26? ________________ Is this element important in
living things? ____ Explain.
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6. Only the lighter elements occur in living things. In particular, living organisms are
composed of about 25 of the elements in the top four rows of the periodic table. For
example, what element has an atomic weight of 40.08 and where does this occur in living
things?
7. Approximately 25 elements occur in living things. Six of these 25 elements are of
critical importance in that they comprise the four major groups of molecules found in
living organisms: carbohydrates, lipids, proteins and nucleic acids. These elements are
called CHNOPS for short.
To Do
Find the six elements in the periodic table and complete the chart below. Learn all you
can about these six atoms.
Table 3. Some Characteristics of CHNOPS
Abreviation
Atom
C
carbon
H
hydrogen
N
nitrogen
O
oxygen
P
phosphorous
S
sulfur
Atomic Number Atomic Weight Group
Questions
8. Which of the other five elements in CHNOPS is most like oxygen?
9. Which of the other five elements in CHNOPS is most like nitrogen?
10. Which element in CHNOPS has the greatest mass?
11. Which element in CHNOPS has the least mass?
Describe
12. Describe how your body obtains oxygen.
13. What is the primary means by which your body obtains phosphorus, carbohydrates
and fats?
14. How does your body obtain the hydrogen it needs?
15. Can your body obtain what it needs by eating carbohydrates or fats alone? Which of
the CHNOPS elements are completely absent from carbohydrates and fats?