Scientists try to find out about the world through investigation and experimentation, but they also take advantage of previous work and consult reports presented by other scientists. These reports are often to be found in scientific magazines, books, the Internet or even, in the case of information that has been known for a long time, in an encyclopaedia.
In this topic you will be accessing material from books, charts, the Internet and even from material around your own home.
Chemists like to use symbols and formulas to represent elements and compounds.
Symbols are a shorthand way of showing information about substances. All of the symbols for elements that chemists use are recorded on a chart called the periodic table. This table was the brilliant idea of a Russian scientist Dimitri Mendeleev.
Look at the periodic table. Each element has a box with the information shown below. There may be a lot of other information, but that can be ignored for now.
| 1
H Hydrogen 1.007 |
atomic number
symbol name relative atomic mass |
This information is almost all you need to know about any element to start with.
The atomic number indicates the element's place in the periodic table. It also is the number of protons in the nucleus of any atom of that element.
The relative atomic mass is the mass of an average atom of the element relative to the mass of a oxygen atom with eight protons and eight neutrons. That oxygen atom is assigned a mass of 16, and the relative atomic mass listed for an atom is a ratio of its mass to oxygen's. In this example 16 hydrogen atoms would have a mass slightly more than one oxygen atom (1.007 x 16 = 16.112). As with all ratios, there are no units.
As you look over the periodic table you will notice that some elements are common substances which you know well while others are ones you have probably never heard of. To help you become familiar with some of the elements, answer the following questions using the periodic table as a guide.