Question

the family of non metals having valency one

Answer 1

Elements may be categorized according to element families. Knowing how to identify families, which elements are included, and their properties helps predict behavior of unknown elements and their chemical reactions.

What Is an Element Family?

An element family is a set of elements sharing common properties. Elements are classified into families because the three main categories of elements (metals, nonmetals and semimetals) are very broad. The characteristics of the elements in these families is determined primarily by the number of electrons in the outer energy shell. Element groups, on the other hand, are collections of elements categorized according to similar properties. Because element properties are largely determined by the behavior of valence electrons, families and groups may be one and the same. However, there are different ways of categorizing elements into families. Many chemists and chemistry textbooks recognize five main families:

5 Element Families

alkali metalsalkaline earth metalstransition metalshalogensnoble gases

9 Element Families

Another common method of categorization recognizes nine element families:

Alkali Metals - Group 1 (IA) - 1 valence electronAlkaline Earth Metals - Group 2 (IIA) - 2 valence electronsTransition Metals - Groups 3-12 - d and f block metals have 2 valence electronsBoron Group or Earth Metals - Group 13 (IIIA) - 3 valence electronsCarbon Group or Tetrels - Group 14 (IVA) - 4 valence electronsNitrogen Group or Pnictogens - Group 15 (VA) - 5 valence electronsOxygen Group or Chalcogens - Group 16 (VIA) - 6 valence electronsHalogens - Group 17 (VIIA) - 7 valence electronsNoble Gases - Group 18 (VIIIA) - 8 valence electrons

Recognizing Families on the Periodic Table

Columns of the periodic table typically mark groups or families. Three systems have been used to number families and groups:

The older IUPAC system used Roman numerals together with letters to distinguish between the left (A) and right (B) side of the periodic table.The CAS system used letter to differentiate main group (A) and transition (B) elements.The modern IUPAC system uses Arabic numbers 1-18, simply numbering the columns of the periodic table from left to right.

Many periodic tables include both Roman and Arabic numbers. The Arabic numbering system is the most widely accepted method used today.

Answer 2

halogen family and sulphur are nonmetals having valency one