Page 71 - Science at the nanoscale

RPS: PSP0007 - Science-at-Nanoscale
7:6
June 12, 2009
Chapter Four
From Atoms and Molecules
to Nanoscale Materials
The discovery of the atom as the basic fundamental unit of matter
discussed in Chapter 3 has allowed scientists to see matter as an
ensemble of atoms held together by interatomic forces. In this
chapter, we will discuss some fundamental concepts and interac-
tions that describe how these ensembles are held together to form
solids and materials.
ATOMS AND THE PERIODIC TABLE OF
4.1
ELEMENTS
In Section 3.3, the Schr¨odinger equation was solved for the one-
electron hydrogen-like atom and an equation for atomic energy
states was obtained:
RhcZ 2 ch04
E n = − 2 (3.57)
n
This is a general equation as Z is the atomic number (i.e. number
of protons in the nucleus) that uniquely identifies a chemical
element. In the eighteenth century, scientists such as Dmitri
Mendeleev found that when known elements are tabulated
according to increasing Z values, the periodicity or trend of chem-
ical properties can be arranged in an orderly pattern into the
Science at the Nanoscale: An Introductory Textbook
by Chin Wee Shong, Sow Chorng Haur & Andrew T S Wee
Copyright c
2010 by Pan Stanford Publishing Pte Ltd
www.panstanford.com
978-981-4241-03-8