Grade 9E1
Periods: 1&2: 8:30 a.m. -9:50 a.m.
Chemistry
March 25, 2022
Topic: The Periodic Table of Elements
PLEASE COPY DOWN THE FOLLOWING NOTES IN YOUR CHEMISTRY NOTEBOOKS
What is the periodic table?
The periodic table of elements is a tabular organization of pure substances that can use in analysing
reactivity among elements, predicting chemical reactions, and understanding trends in periodic properties
among different elements and speculate on the properties of those yet to be discovered.
The modern periodic table arranges the elements by their atomic numbers and periodic properties.
The following information can be determined from each block or tile of the table:
1. Atomic Symbol
2. Atomic Number
3. Atomic Mass
4. Name of Element
5. Electron Configuration
History of the Periodic Table
Several scientists worked over almost a century to assemble the elements into this format. Below are Five
(5) of the scientist who are considered to have made very significant contributions:
1. Democritus (460-370 B.C.): He was a Greek philosopher who is credited to have first to come up with
the term “atomos” which he called the particles of a substance he believed to be indivisible. His belief was
that if one took a substance such as a metal and cut it into the tiniest piece possible then eventually one
would reach a point where the metal could no longer be cut smaller and thus, he called those tiny particles
the atomos. Atomos were believed back then to be made of the same matter, but had different shape and
sizes.
2. John Dalton (September 5 or 6, 1766—July 27, 1844): He was a British scientist who developed the
atomic theory which attempted to explain the structure of explain the structure of elements and compounds.
His theory established the way for the atomos to be called atoms and although, parts of his theory were
eventually determined to be incorrect other aspects were on point.
3. Johann Wolfgang Dobereiner (13 December 1780 – 24 March 1849): He was a German Chemist. In
1817, He showed that elements could be arranged in “triads”, sets of threes based on their similar
properties. He arranged elements in groups of three in increasing order of atomic weight, observing that
some properties of the middle element, such as atomic weight and density, approximated the average value
of these properties in the other two in each triad. His work is best known for foreshadowing the periodic
law for the chemical elements.
4. John Newlands (November 26, 1837—July 29, 1898): He was a British chemist, who was first to show
that elements could be arranged in order their atomic masses and shared chemical properties. He found that
every eight elements had similar properties and called this the law of octaves. He arranged the elements in
eight groups but left no gaps for undiscovered elements.
5. Dmitri Mendeleev (February 8, 1834--February 2, 1907): He was a Russian scientist considered to be
the Father of the modern periodic table. Mendeleev created the framework that became the modern periodic
table, leaving gaps for elements that were yet to be discovered. While arranging the elements according to
their atomic weight, if he found that they did not fit into the group he would rearrange them. Mendeleev
predicted the properties of some undiscovered elements and gave them names. Another Scientist named
Davy Meyer, also created a periodic table similar to Mendeleev’s but did not leave any gaps. Even though
some discrepancies with Mendeleev’s periodic table that could not be explained; the later discovery of
elements predicted by Mendeleev, including gallium (1875), scandium (1879) and germanium (1886),
verified his predictions and his periodic table won universal recognition.
Project Homework (Due next Class April 1st, 2022): Use The first twenty (20) Elements on the periodic
table to create a board game. You can use cartridge paper backed by cardboard or a piece of wooden board.
Write the instructions for playing your game on a small piece of cartridge paper or blank paper. You will be
marked on your innovation, creativity, presentation, content knowledge of the first 20 elements in
creating your board. You will be expected to explain how your game is played to the class in a show and tell
experience.
CLASS ACTIVITY: COMPLETE THE WOIRKSHEET ATTACHED BY USING TH PERIODIC
TABLE AT THE FRONT OF THE NOTES TO HELP YOU. PLEASE WRITE ON THE WORKSHEET
PROVIDED. THE TEACHER ASSGNED WILL COLLECT THE NOTE SHEETS AND WORKSHEET
AST THE END OF THE SESSION.