Dust and Planets
We can now watch how atoms begin to interact with each other. Things are going to be a lot more interesting from now on, as gradually larger and more complex assemblies of atoms joined together, ultimately creating you and me!
But the story starts in a fairly simple way.
We have seen that a or are major ways in which the new, heavy nuclei made in stars are sent out into the , ready to be incorporated into new stars and . If this re-cycling did not happen, planets and could never have begun.
As they shot out of the star, some nuclei gained too many (giving them a negative ) while others had too few (giving them a positive charge). This type of atom is called an ion.
An ion is an which has lost or gained an . Such an atom carries an , so it will strongly attract or repel other ions.
If a meets a positive one, their opposite charges attract strongly and glue the together. This type of gluing is called an ionic bond.
Ionic bonds were first formed as emerged from a . They are important today in holding the atoms together in many rocks on the Earth, as well as materials like table salt.
When a lot of positive and negative ions meet they can form a solid with a regular arrangement of atoms, called a crystal, as shown in the next diagram.
Ionic bonds hold atoms strongly together
Because the ionic bond is strong, many crystals were able to form and survive even in the hot gas surrounding an exploding star.
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