Download PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY

PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
PLCMETS Inquiry Resources Collection:
The Periodic Table
Current TEKS:
8.9 B: interpret information on the periodic table to understand that physical properties are used to
group elements
Future TEKS:
6.5 A: elements are pure substances represented by chemical symbols
7.3 D: relate impact of research on scientific thought
8.2 A: plan and implement comparative and descriptive investigations by making observations,
asking well-defined questions, and formulating testable hypotheses
8.5 B: identify that protons determine an element's identity and valence electrons determine its
chemical properties
8.5 C: interpret the arrangement of the Periodic Table
Scope and Sequence:
Aldine: Grade 8, 1st six weeks
Cy-Fair: Grade 8, 1st six weeks
Big Ideas:
An element is a pure substance of one type of atom that is represented by a chemical symbol. An
example is hydrogen, which is an element comprised exclusively of hydrogen atoms and is
represented by the chemical symbol, H. Currently, 115 elements are known, but only about 90 are
found in Nature.
The periodic table of elements is a tabular representation of chemical elements with distinct trends.
The rows (periods) are arranged so that elements are listed in order of increasing atomic number,
which is the number of protons in the nucleus of each atom. Rows are arranged so that elements
with similar chemical or physical properties fall into vertical columns called groups or families.
Prominent groups include alkali metals, alkaline earth metals, halogens, and noble gases. Regions
of the periodic table are also broken up into two different regions: main group (or representative)
elements and transition elements. An 'unknown' element's properties can be identified by
examining the row and the group it is in.
Valence electrons determine an element's chemical properties, which includes reactivity.
Reactivity is the term that refers to just how likely a particular element (or molecule, atom, etc.) is
to react with other substances. They vary from being virtually unreactive like the noble gases
whose valence (outermost) electron shell is completely full and thus is vary stable (unreactive) to
the alkali metals who have one electron in the valence electron shell and are very reactive (like
when exposing an alkali metal to water). To see alkali metals reacting with water, see this 1:19
min. video from youtube.
For more information, see How the Periodic Table Works from HowStuffWorks.com
Page | 1
PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
The Periodic Table
http://www.chemeddl.org/collections/TSTS/PeriodicTable.gif
The Grabber:
YouTube video of the Element Song. A cute, slightly outdated song listing each element by name.
Case Study:
Dmitri Mendeleev, the Russian professor and chemist, is credited with conceptualizing the first
periodic table. Mendeleev overcame sickness and strife in his youth to become a professor at Saint
Petersburg State University. After becoming a teacher, he wrote the Principles of Chemistry (18681870). "By attempting to classify the elements according to their chemical properties, he noticed
patterns that led him to postulate his Periodic Table. On March 6, 1869, Mendeleev made a formal
presentation to the Russian Chemical Society, entitled The Dependence between the Properties of
the Atomic Weights of the Elements, which described elements according to both atomic weight
and valence. This presentation stated that:
1. The elements, if arranged according to their atomic weight, exhibit an apparent periodicity of
properties.
2. Elements which are similar in regards to their chemical properties have atomic weights which are
either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).
3. The arrangement of the elements in groups of elements in the order of their atomic weights
corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical
properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F.
4. The elements which are the most widely diffused have small atomic weights.
5. The magnitude of the atomic weight determines the character of the element, just as the
magnitude of the molecule determines the character of a compound body.
6. We must expect the discovery of many yet unknown elements–for example, two elements,
analogous to aluminium and silicon, whose atomic weights would be between 65 and 75.
Page | 2
PROFESSIONAL LEARNING COMMUNITY MODEL FOR ENTRY INTO TEACHING SCIENCE
A professional learning community of STEM educators, scientists, and engineers
http://plcmets.pbworks.com/
7. The atomic weight of an element may sometimes be amended by a knowledge of those of its
contiguous elements. Thus the atomic weight of tellurium must lie between 123 and 126, and
cannot be 128. Here Mendeleev was wrong as the atomic mass of tellurium (127.6) remains
higher than that of iodine (126.9).
8. Certain characteristic properties of elements can be foretold from their atomic weights."
(http://en.wikipedia.org/wiki/Mendeleev)
One form of Mendeleev's Periodic Table
(http://en.wikipedia.org/wiki/File:Mendeleev_Table_5th_II.jpg)
Good Research Questions:
What groups are there in the periodic table and how are they characterized?
How are they characterized?
Not so good Research Questions:
How does reactivity help establish a pattern in the periodic table?
Simulated Research Activities:
Simulation: Interactive Periodic Table - click on an element in the periodic table and see its
physical & chemical characteristics and its descriptions
Dataset Analysis: Graphing Trends in the Periodic Table Inquiry Project (requires graphing
calculator or Microsoft Excel)
Short Videos you may find useful:
How the elements are organized (http://videos.howstuffworks.com/hsw/8205-the-periodic-tablehow-the-elements-are-organized-video.htm) - 2:54 min video that shows great examples of alkali
metals exploding when they touch water and different characteristic traits of different groups
The history of the Periodic Table (http://videos.howstuffworks.com/hsw/14741-simply-sciencethe-history-of-the-periodic-table-video.htm) - 1:26 min video that is also very good in explaining
how the elements are organized)
Page | 3