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Lesson: Chapter 3 — The Structure of Matter

3.6. Metals, non-metals and metalloids 1 of 10

The staircase line

Draw a line through the long form of the periodic table, stepping down from boron (B) to astatine (At) like a staircase. That line sorts the elements into three kinds.

Figure to be added

Figure 3.11: the long form of the periodic table, with the staircase line running from boron to astatine; metals shaded on the left, non-metals on the right, metalloids in the boxes along the line itself, and the noble gases marked in the last column.
Where it is What it is
To the left of the line Metals
To the right of the line Non-metals
Along the staircase itself Metalloids

Why the elements on the line get their own name

The elements lying around the staircase have properties intermediate between metals and non-metals — neither one thing nor the other — so they are called metalloids.

One of the three is far larger than the others. Of the elements identified so far, about 80 per cent are metals. The rest of this section takes each kind in turn.