GROUP 17 BONDING
the HALOGENS
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Bond mainly by ionic bonding to become 1- ions with
noble gas configurations.
The ions are isoelectronic to the noble gas of the SAME
period, which is the kernel of that element.
High electronegativity and High ionization energy causes
an electron to be gained, completing the p sublevel and
the outer shell octet.
As you read down the group, electronegativity, ionization
energy and nonmetal reactivity DECREASE, atomic
radius INCREASES. See concept map.
All negative ions are larger than the neutral atom from
which they are derived, due to a gained electron.
EXAMPLES
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The configuration of Neon
1s2↑↓
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The configuration of FLOURINE (ground)
1s2↑↓
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2s2 ↑↓ 2p6 ↑↓ ↑↓ ↑↓
2s2 ↑↓ 2p5 ↑↓ ↑↓ ↑_
The configuration of FLOURIDE ION [F]1-
1s2↑↓
2s2 ↑↓ 2p6 ↑↓ ↑↓ ↑↓
AFFINITY and REDUCTION
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The addition of an electron is called ELECTRON AFFINITY, the
energy that is evolved to do so is called AFFINITY ENERGY. This
process is exothermic – energy releasing, the energy must have a
sink that will absorb it..
In the diagram below, the following is important:
1. The electron gained will most likely be obtained by from a metal.
2. The resulting ion is isoelectronic to the noble gas of the same period.
3. AFFINITY ENERGY is released.
F + 1e- 
The electron
is from
another
atom
1s2↑↓
2s2 ↑↓ 2p5 ↑↓ ↑↓ ↑
+
1e-

F[Ne]1s2↑↓
2s2 ↑↓ 2p6 ↑↓ ↑↓ ↑↓