Question

Write the name from the description.
The family of nonmetals having valency one.

Answer 1

Valency of any element is the number of electrons required by an element to complete a noble gas configuration. Here, to attain complete configuration an atom can either accept or donate as much as electrons require.

Complete step-by-step answer
Electrons of an element or atom are distributed and arranged in the orbits or shells. According to Bohr-bury rules, the last shell of the element can contain a maximum of 8 electrons. The last orbit of a noble gas has a complete configuration that is their last orbit is completely filled making them non-reactive or less reactive and stable. All other elements have incomplete last orbital, hence they lose or gain or even share electrons to complete the octet. The electrons present in the outermost shell which can be involved in bonding are known as valence electrons, e.g. Magnesium (Mg) has an atomic number 12 and contains 2 electrons in the outermost orbit, and hence its valency will be 2. In the periodic table, elements belonging to the same group have the same valency.
Group 17 of the periodic table consists of highly reactive nonmetals. As they are 1 electron short to complete their octet, they can readily take up an electron to attain stability which makes them more electronegative, e.g. Chlorine (Cl) atoms have 7 electrons in its outermost orbit and can gain one electron from other elements, therefore we can say Cl is highly reactive and electronegative.
Hence, the family of nonmetals having valency one will be all the elements from group 17 that are halogens. Example Florine (F), Chlorine (Cl), Bromine (B), etc.

Note:
Few elements lose or gain electrons to form an ion. This is known as electrovalency. When an element loses an electron to form a positive ion it is said to be positive electrovalency and when an element gains one electron to form a negative ion it is known as negative electrovalency. Covalency is the property where an element shares one or more electrons to form a compound.