Ions and ionic bonds
Introduced| English | Meaning |
|---|---|
| ion/ˈaɪɒn/ | An atom or group of atoms with a net electric charge from losing or gaining electrons. |
| cation/ˈkætaɪən/ | An ion with a positive electric charge. |
| anion/ˈænaɪən/ | An ion with a negative electric charge. |
| ionic bond/aɪˈɒnɪk bɒnd/ | The electrostatic attraction between oppositely charged ions. |
Atoms that gain or lose electrons
- Atoms are happiest with a full outer shell. Many achieve this by giving away or taking electrons.
- An atom that has gained or lost electrons becomes a charged ion 离子.
When a metal atom forms an ion, it:
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Metals lose electrons, becoming positive.
A non-metal atom gains electrons to form a ______ ion.
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Extra electrons give a negative charge.
Forming ions
- A metal atom loses outer electrons to form a positive ion (cation 阳离子).
- A non-metal atom gains electrons to form a negative ion (anion 阴离子).
Sodium gives its outer electron to chlorine; both reach full outer shells and the opposite charges attract
Forming an ionic bond (NaCl)
Step through it. A metal hands its outer electron to a non-metal; the oppositely charged ions then attract and pack into a giant lattice.
Ionic bonding (electron transfer)
Step through it: the metal hands its outer electron(s) to the non-metal, both reach full shells, and the resulting + and − ions attract — an ionic bond.
An ionic bond is the attraction between:
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Oppositely charged ions attract.
In ionic bonding, electrons are transferred from the metal to the non-metal.
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The metal loses and the non-metal gains.
Ionic bonding 离子键
- An ionic bond is the strong attraction between oppositely charged ions.
- Electrons transfer from the metal to the non-metal, and the ions then attract.
Worked example. Sodium (2,8,1) gives its 1 outer electron to chlorine (2,8,7). Sodium becomes Na⁺ and chlorine becomes Cl⁻. The opposite charges attract — an ionic bond in sodium chloride.
An element in Group I forms an ion with a charge of:
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Group I loses 1 electron → +1.
Working out the charge
- The charge equals how many electrons are lost or gained.
- Group I → +1, Group II → +2; Group VII → −1, Group VI → −2.
Metals lose, non-metals gain. Losing electrons leaves more protons than electrons → a positive ion. Gaining electrons gives more electrons than protons → a negative ion.
You've got it
- an ion is a charged atom that has lost or gained electrons to fill its outer shell
- metals lose → positive ions; non-metals gain → negative ions
- an ionic bond is the attraction between oppositely charged ions