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The Halogens/Group 7
The Halogens have 7 valence electrons in their outer shell, and is also known as Group 7. All halogens exist as diatomic molecules which means that they exist as molecules, each molecule a pair of the same atom e.g. Cl .In symbol equations instead of Cl, Cl
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In displacement reactions, a less reactive element is displaced or replaced by a more reactive element.E.g.:
chlorine + sodium bromide→sodium chloride + bromine
Cl + 2NaBr → 2NaCl + Br
In the equation above, Chlorine takes the place of Bromine because it is more reactive than it. However a less reactive element cannot displace an element that is more reactive than it
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The members of the Halogens include:
-Fluorine (F)
-Chlorine(Cl)
-Bromine (Br)
-Iodine (I)
-Astatine (At)
Things the Halogens have in common/Trends:
-They all have 7 valence electrons, which means that their last outer shell has 7 electron in it. (E.g. Chlorine's outer shell configuration is 2,8,7.)
-As you go down the group, the Halogens colour goes darker: Fluorine is a pale yellow, Chlorine is yellow-green,Bromine is red-brown, Iodine is shiny purple
-As you go down the group, their reactivity decreases, while their boiling and melting points increases
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Bonding:
-Group 7 metals bond with other elements using ionic bonds which are held together by electrostatic bonds.
-However instead of giving away their 7 valence electrons, they receive it from the elements they are bonding with. For example in NaCl, Chlorine receives Sodium's valence electron thus becoming a Chlorine ion. This Chlorine ion has a negative charge because now there are more electrons(18) than there are protons(17)-Thus becoming a negative ion
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At room temperature, Fluorine and Chlorine are gases, Bromine is a liquid and Iodine is a solid, we do now know much about the properties of Astatine is a solid and possibly black in colour-It is highly radioactive that is why it is hard to find out what properties Astatine has.
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