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Nonmetals

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Nonmetals

Parts needing to be sorted

When we sort parts in our shop or garage, we often classify them in terms of common properties.  One container might hold all the screws (possibly sub-divided by size and type).  Another container would be for nails.  Maybe there is a set of drawers for plumbing parts. 

When you get finished, you could also have a collection of things that don’t nicely fit a category.  You define them in terms of what they are not.  They are not electrical components, or sprinkler heads for the yard, or parts for the car.  These parts may have some common properties, but are a variety of items.

Non-Metals 

In the chemical world, these “spare parts” would be considered non-metals, loosely defined as not having the properties of metals. A nonmetal is an element that is generally a poor conductor of heat and electricity. Most properties of nonmetals are the opposite of metals. There is a wider variation in properties among the nonmetals than among the metals.  Nonmetals exist in all three states of matter. The majority are gases, such as nitrogen and oxygen. Bromine is a liquid. A few are solids, such as carbon and sulfur. In the solid state, nonmetals are brittle , meaning that they will shatter if struck with a hammer. The solids are not lustrous. Melting points are generally much lower than those of metals.   The green elements in the table below are non-metals.

The periodic table

Non-metals have a wide variety of uses.  Sulfur can be employed in gunpowder, fireworks, and matches to facilitate ignition (see Figure below ).  This element is also widely used as an insecticide, a fumigant, or a means of eliminating certain types of fungus.  An important role for sulfur is the manufacture of rubber for tires and other materials.  First discovered in 1839 by Charles Goodyear, the process of vulcanization makes the rubber more flexible and elastic as well as being more resistant to changes in temperature.  A major use of sulfur is for the preparation of sulfur-containing compounds such as sulfuric acid.

Solid elemental sulfur

Sulfur.

Bromine is a versatile compound, used mainly in manufacture of flame-retardant materials, especially important for children’s clothing (see Figure below ).  For treatment of water in swimming pools and hot tubs, bromine is beginning to replace chlorine as a disinfectant because of its higher effectiveness.  When incorporated into compounds, bromine atoms play important roles in pharmaceuticals for treatment of pain, cancer, and Alzheimer’s disease.

Elemental bromine

Bromine.

Helium is one of the many non-metals that is a gas.  Other non-metal gases include hydrogen, fluorine, chlorine, and all the group eighteen noble (or inert) gases.  Helium is chemically non-reactive, so it is useful for applications such as balloons (see Figure below ) and lasers, where non-flammability is extremely important.  Liquid helium exists at an extremely low temperature and can be used to cool superconducting magnets for imaging studies (MRI, magnetic resonance imaging).  Leaks in vessels and many types of high-vacuum apparatus can be detected using helium. Inhaling helium changes the speed of sound, producing a higher pitch in your voice.  This is definitely an unsafe practice and can lead to physical harm and death.

Goodyear blimp contains helium gas

Blimp.

Summary  

  • Non-metals are generally poor conductors of heat and electricity.
  • Properties of non-metals are usually the opposite of properties of metals
  • Non-metals can be solid, liquid, or gas at room temperature depending upon the element.
  • Sulfur, bromine, and helium are typical non-metals.

Practice

Questions

Select two non-metals from the periodic table that have not been mentioned.  Locate information to answer the following questions:

  1. What are the physical properties of this non-metal?
  2. List three current uses for this element.

Review

Questions

  1. What are the properties of non-metals?
  2. List the states of matter in which non-metals can exist and give one example of each state
  3. What are the physical properties and uses of sulfur?
  4. What are the physical properties and uses of bromine?
  5. What are the physical properties and uses of helium?

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