Chemical Families
Objectives
Takes you on a guided tour of the Periodic Table
Describes the similarities and changes in the properties of the members
of selected groups of the table
Introduces the chemistry of the d-block elements transition elements
Looks at trends in the properties of the elements across a period of the
table
Periodic Table
At first glance, the known elements present a bewildering array of different properties.
Sodium, for example, is a very reactive solid that has a shiny appearance and conducts
electricity, whereas neon is a non-conducting gas that does not react with anything.
How do chemists organise the elements so that they can explain the properties of
known elements and predict the properties of, as yet, undiscovered elements?
The Russian chemist Dimitri Mendeleev made a major contribution to chemistry
when he presented his Periodic Table 1869. The arrangement of the elements in that
Periodic Table arose from observations that certain groups of elements show similar
properties. For example F 2 , Cl 2 , Br 2 and I 2 are all coloured, volatile, poisonous and
reactive non-metals, whereas Li, Na and K are all soft, light metals that tarnish in air.
The modern-day Periodic Table, shown on the inside front cover of this book, has
the atoms of elements listed in order of increasing atomic number. The numbered
vertical columns are called groups(orfamilies) and elements in the same group
often have similar properties. Some of the groups have special names:
1.Group 1 elements (Li, Na, K, Rb, Cs and Fr) are called the alkali metals.
2.Group 2 elements (Be, Mg, Ca, Sr, Ba and Ra) are the alkaline earth metals.
3.Group 15 elements (N, P, As, Sb and Bi) are (rarely) called the pnicogens.
4.Group 16 elements (O, S, Se, Te and Po) are sometimes referred to as the
chalcogens.
5.Group 17 elements (F, Cl, Br, I and At) are commonly known as the halogens.
6.Group 18 elements (He, Ne, Ar, Kr, Xe and Rn) are the noble gases.
12.1
Contents
12.1Periodic Table 19312.2Group 1 elements 19412.3Group 2 elements 19712.4Group 14 elements 19912.5Group 17 elements 20312.6Group 18 elements 20412.7Elements of the
first transition
series 20512.8Variation of
properties of
elements within
groups and periods 21012.8Revision questions 21412
UNIT