How do atoms join into molecules?
Atoms join by sharing or handing over some of their outer electrons. The pull that then holds them together is called a chemical bond.
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Chemistry
How atoms join, split and swap partners — molecules, bonds and reactions.
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What it is and why it matters — intuition first, little or no math.
What is a chemical element?
A chemical element is a pure substance made of only one kind of atom, like gold or oxygen. Which element it is depends on one number, the number of protons in each atom.
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What is a chemical reaction?
In a chemical reaction, atoms let go of their old partners and join new ones, so new substances form. No atom disappears and no new atom appears.
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What are electron shells?
The electrons of an atom sit in layers around its nucleus, called electron shells. Each shell has room for only so many electrons, and the outer shell decides how the atom behaves.
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What is an ion?
An ion is an atom that has lost or gained one or more electrons. Because its plus and minus charges no longer balance, it carries an electric charge.
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What is a molecule?
A molecule is a group of atoms held together by chemical bonds. A water molecule, for example, is two hydrogen atoms joined to one oxygen atom.
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How does the periodic table work?
The periodic table is a chart of all the chemical elements, in order of how many protons their atoms have. It is cut into rows so that elements that behave alike stand in the same column.
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