Download 2.5-The Periodic Table

The Periodic Table
Mendeleev was a Russian scientist who is
credited with the development of the
periodic table – a table that classifies and
groups all known elements.
Mendeleev knew the properties of the
elements, such as colour, density, boiling
point, and atomic mass (the average mass of
an atom of an element). He created cards for
each element and began arranging the
elements in vertical columns and horizontal
rows.
After many months he noticed a pattern
occurred when he placed the cards in order
of increasing atomic mass (known today as the
periodic law). Properties of elements were
repeated both within rows and in columns.
At the time, there were only 58 known
elements. So Mendeleev left spaces in his
table assuming an undiscovered element would
take its place. He predicted the properties
of the “unknown” elements, and within the
next sixteen years those gaps were filled in
with newly discovered elements that matched
precisely with Mendeleev’s predictions!
Activity – Chemical solitaire. Page 127. Hand
in the arrangement of your best grouping and
questions #1-3.
Read page 126-128.
The modern periodic table (page 441) has
elements that are arranged by increasing the
atomic number.
The periodic table includes the following
information for each element:
1) Symbol
2) Element name
3) Atomic number – number of protons
an element has in its nucleus. (examples)
4) Atomic mass
a. the average mass of an atom of an
element.
b. = Number of protons + number of
neutrons
c. examples – such as how many
neutrons in F?
Work on investigation 2-D on pages 129 -131.
(handout BLM 2-10). Answer ALL questions.
The periodic table is arranged into:
- rows – called periods. The trend within a
period is increasing atomic mass.
- Columns – called groups or families. The
trend within a group is the elements
share similar reactivity.
BLM 2-11
BLM 2-12
Read chapter. Answer questions #1-4 on page
135.