Page 52 - 新思维科学学生用书7 样章
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2.5 Atoms, elements and the Periodic Table
Questions
1 What are atoms?
2 If there are 94 different kinds of naturally occurring atom, how many different naturally
occurring elements are there?
Atoms joining together
In six of the elements, such as neon (which is a gas), atoms move around freely, not attached to one
another. But in most elements, such as gold and other metals, atoms are packed closely together.
In a small number of elements, such as oxygen and sulfur, atoms join together to form small particles.
An oxygen particle is made from two oxygen atoms. A sulfur particle is made from eight sulfur atoms.
Atoms of neon Atoms of gold
Particles of oxygen Particle of sulfur
Arranging the elements
Scientists have developed a very useful way of arranging the elements. This is called the Periodic
Table.
The full Periodic Table containing all of the 118 known elements (that is 94 natural and 24 man-made)
is very large and complex. (There may be one on the wall of your science laboratory.) You are just going
to look at the first 20 elements.
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