UNIT 5 - THE PERIODIC LAW
History of the Periodic Table
I. Mendeleev and
Chemical Periodicity
A. Wanted to organize elements according to their
____________________
B. When elements were arranged in order of increasing
atomic mass*, similarities in chemical
properties appeared at regular
intervals (____________________)
C. *Several elements did not quite fit this pattern -
Mendeleev put elements with similar
____________________ in the same
column or group
D. 1871 - Mendeleev predicted the existence and
properties of several (then undiscovered)
elements. These elements were:
E. Within 15 years, those
elements with those properties had been discovered
II.
Moseley and the Periodic Law
A. When elements were arranged in order of increasing
___________________________________,
there was a distinct regular
pattern.
B. ____________________:
The physical and chemical properties of the elements are periodic
functions of their atomic
numbers.
C. In other words, when elements are arranged in order
of increasing atomic number, elements
with similar properties appear
at regular intervals.
D. Bottom line = elements in the same group have
similar properties
III.
Modern Periodic Table: arrangement of the elements in order of
their atomic numbers so that elements with similar properties fall in the same
group
Electron Configuration and the Periodic Table
I. Stability of
Noble Gases
A. Noble gases undergo very few chemical reactions -
why?
B. Highest occupied energy level contains
________________________________________
C. Electrons in the highest occupied energy level are
what determines an element's _____________
II. Periods and Blocks of the Periodic Table
A. Horizontal row = ____________________; 7 on modern Periodic Table
B. Length of period determined by
the sublevels being filled in that period
C. Period 1: only _____ sublevel being
filled; can hold a maximum of _____
electrons;
period contains _____ elements
D. Period 4: ____, ____, and ____ sublevels
being filled; s can hold ___ electrons, d can hold ___
electrons, & p can hold ___
electrons; total of _____ electrons;
Period 4 contains _____ elements
E. Period can be determined from the element's
electron configuration
1. Bromine: [Ar] 4s2 3d10 4p5
2. Highest number in front of
letter is the element's highest occupied _____________________ -
tells
which period the element is in
3. For bromine, _____ is
highest number, so it is in Period _____
III.
The "s" block elements: Groups 1 and 2
A. Group 1 - Alkali Metals
1. generalized
outermost energy level (valence) electron configuration:
2. silvery appearance
3. soft
enough to cut with a knife
4. not
found in nature as free elements - they're always part of a compound
5. with
increasing atomic number, melting point ______________________
B. Group 2 - Alkaline Earth Metals
1. generalized
valence electron configuration:
2. harder, stronger, more
dense than Group 1
3. also
have higher melting points than Group 1
4. less
reactive than Group 1, but still not found in nature as free elements
C. Exceptions: Hydrogen and Helium
1. Hydrogen
(H)
a.
electron configuration:
b.
properties do not resemble those of any other element on the periodic table
2. Helium
(He)
a.
electron configuration:
b. in
Group 18 because
IV.
The "d" block elements: Groups 3 - 12
A. called
B. have typical metallic
properties: ductile, malleable, shiny, solid, conduct electricity
C. less reactive than
"s" block elements
D. found in nature as free
elements
E. usual ending of electron
configuration:
V. The "p"
block elements: Groups 13 - 18
A. "s" and
"p" block elements together referred to as
_____________________________ elements
B. ending electron
configurations of __________________ through ___________________
C. properties vary greatly
b/c there are metals, metalloids, and nonmetals
D. Group 17 - Halogens
1. most
reactive nonmetals
2. seven
electrons in outermost energy level
E. "p" block metals
are harder and more dense than "s" block , but not as hard or dense
as the "d"
block metals