11Introduction to Nanosensors
number 118 have been made in laboratory. According to theoretical predic-
tions, the highest atomic number lies between 170 and 210.
Hydrogen is the most abundant element in the universe (90.7% by mass)
while oxygen is the most abundant element in the earth’s crust (47.4% by
mass). Tungsten (W) has the highest melting and boiling points (M.P. = 3407°C
and B.P. = 5657°C).
1.4.6 Metals, Nonmetals, and Metalloids
Elements are divided into three classes: metals, nonmetals, and metalloids.
Metals form positively charged ions (cations) by the loss of electrons from
their atoms; they have positive valency. Nonmetals form negatively charged
ions (anions) by gain of electrons by their atoms; they have negative valency. ...