An element is a substance composed of one type of atom only. There are 92 naturally occurring atoms, and hence the same number of elements, that make up our Universe. The properties of the elements are described by measures such as state, lustre, malleability, colour, melting point, boiling point, density, electrical and heat conductivity and the type of ions they form.

When these measures are applied to the elements they fall into two main camps with a few elements with "a foot in both camps!" This topic investigates the two main types of elements and how to tell them apart.

Measuring the elements
For simplicity four properties will be tested in this section to divide the elements into their respective camps: state, lustre, malleability, electrical conductivity and ion formation.

State: (solid, liquid or gas)

• gas - 11 elements
  
• liquid - 2 elements
  
• solid - 79 elements

Lustre: (the ability to reflect light when polished)

• Reflect light well - 75 elements
  
• Do not reflect well - 17 elements

Malleability: (the ability of a solid to be beaten into a sheet and to bend)

• Bend when hit with a hammer - 69 elements
  
• Break or shatter when hit* - 23 elements

* Note: Gases and liquids are included here.

Electrical conductivity: (will pass or conduct an electric current)

• Good conductors - 68 elements (approximate figures)
  
• Poor conductors - 16 elements
  
• Semiconductors - 8 elements

Ion formation: (atoms either gain electrons to form negative ions, lose electrons to form positive ions or do not easily form ions at all.)

• Form positive ions - 73 elements
  
• Form negative ions - 7 elements
  
• Do not easily form ions - 12 elements

The above measurements show that the majority of elements are lustrous, malleable solids that form positive ions and conduct electricity.

Metals
In fact, the above statement is just about right as the description of the type of elements called "metals".

There are 71 naturally occurring elements recognised as metals.

• All conduct electricity well
  
• All conduct heat well
  
• All have lustre
  
• All form positive ions
  
• All, but one are solids (mercury is a liquid)
  
• Most are quite malleable and ductile (the ability to be drawn into a wire)      

Typical metals are: gold, silver, mercury, iron, aluminium, lead, zinc, chromium, uranium magnesium, calcium and copper to name a few.

Well, what about the other 21 elements? Lets try the opposite properties of metals.

Non-metals
Most are not solids, but liquids and gases. They do not conduct electricity or heat well, are dull, form negative ions and shatter if hit with a hammer (solids only).

There are about 16 elements which have most of these properties. 11 are gases and 1 liquid. 10 commonly form negative ions and 9

• Only 1 conducts electricity well, 9 do not 6 are semi conductors.
  
• None conduct heat well.
  
• Most are dull with no lustre, but there are 6 with lustre like a metal.
  
• Only 1 forms positive ions easily, 7 form negative ions and 13 either will not form ions or do so only occasionally.
  
• Only 4 are solids, 11 are gases and 1 liquid.
  
• None are malleable or ductile.

Typical non-metals are hydrogen, helium, oxygen, sulfur, chlorine, nitrogen and phosphorus.

Metalloids
Defining non-metals is not as easy as metals, because there is such a large range of properties. One group of elements in particular borders in properties between the metals and non-metals. Known as metalloids, these are the elements with "a foot in both camps".

The number of metalloids is not well defined, probably 5 - 7 depending on who you talk to!
Metalloids, typically, are poor conductors of electricity (semi-conductors) form either positive ions or none at all and are not malleable, but most have the metallic lustre. This important group of elements has among its members, silicon, arsenic, boron and selenium.

See the related web topics for more information on the exciting world of the elements.