why does the reactivity of halogens decreases down group 7

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elvin.e
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can someone help me with my chemistry homework?
my teacher also wants me to describe how the trend in reactivity of the halogens down the group differs from that of the alkali metals down the group. I know why group 1 reactivity increases as you go down the group but I am confused on group 7 and why it is different?
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Henri0812
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With group 7 elements, the outer shell has 7 electrons. This means that an electron must be gained. Electrons are attracted to the nucleus, therefore if there is a short distance between the outer shell and the nucleus, it will react more. As you go down the group, there are more electron shells which causes shielding as electrons repel. The more repulsion between electrons, the further away the outer shell will be from the nucleus. This would make it harder for the element with many shells to gain an electron so reactivity will be lower. Hope this helps
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WWEKANE
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because group 7 have 7 electrons on its outer shell so they dont need to lose any electrons also the forces of attraction between + nuclei and electrons increase the further the distance(posative and negative attract) so as we go down group 7 the number of shells(aka energy levels) increases as theres more electrons so its harder for the posative nuclei to attract electrons from other atoms so therefore less reactive

tbis is all u need to know for gcse
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WWEKANE
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more shells sorry*
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CES045
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(Original post by elvin.e)
can someone help me with my chemistry homework?
my teacher also wants me to describe how the trend in reactivity of the halogens down the group differs from that of the alkali metals down the group. I know why group 1 reactivity increases as you go down the group but I am confused on group 7 and why it is different?
Halogens are the opposite to group 1 and group 2 because 1&2 are metals and the halogens are non metals.

What this means is that Halogens GAIN electrons (theyre reduced) from the metals which LOSE electrons (theyre oxidised). Thats why metals form positive ions and halogens form negative ions.

Therefore, the halogen reactivity decreases down the group due to the fact the atomic radius increases and shielding increases down the group as the molecules get bigger as they contain more electron shells, so the attraction between the incoming electron theyre trying to GAIN and the positive nucleus in weaker, so they are unable to attract the electron as easily as higher up halogens which attract the incoming electron with a lot stronger force.

Hope this helps.
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Sabari Suresh
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It has mainly to do with the shielding effect (also called screening effect). Larger atoms (those with greater atomic number, that is) have more electrons between the nucleus and the outer shell. Therefore an outer electron is less strongly attracted to the nucleus, because the bunch of negative charge below it helps to repel it.This makes it more difficult for the atom to attract an extra electron, even though doing so is energically more favorable (because the outer octet becomes filled). If the gaining of an electron is more difficult, the atom is less reactive.
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abdul jimoh x
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cheers mate for the copy and paste it certainly helped i got a 9 in my homework have a good day from Abdul
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ツJcole
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idk I got same question init
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ツJcole
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Cheeeerrrrrrrssss buddddyyyyyyyyyyyy holyyyyyyyyy smartttttttt :u:)
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Ezpic
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Why do they repel?
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Ezpic
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(Original post by Henri0812)
With group 7 elements, the outer shell has 7 electrons. This means that an electron must be gained. Electrons are attracted to the nucleus, therefore if there is a short distance between the outer shell and the nucleus, it will react more. As you go down the group, there are more electron shells which causes shielding as electrons repel. The more repulsion between electrons, the further away the outer shell will be from the nucleus. This would make it harder for the element with many shells to gain an electron so reactivity will be lower. Hope this helps
Why do they repel?
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J Zonda
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(Original post by elvin.e)
can someone help me with my chemistry homework?
my teacher also wants me to describe how the trend in reactivity of the halogens down the group differs from that of the alkali metals down the group. I know why group 1 reactivity increases as you go down the group but I am confused on group 7 and why it is different?
Halogens react by sucking in an electron from anothe rmolecule, as you go down the group, you gain more shells of electrons and thus, your rection force starts to require more energy than it releases, this is known as decreasing enthalpy

With the Alkali metals, the opposite is true
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smasters707
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As you go down group 7, the outer shell becomes further away from the nucleus and to become an ion it must gain one electron; The electrons are attracted to the nucleus meaning the further down the group you go, the harder it is to gain an electron, creating a smaller reaction because more energy is needed to create an ion.Hope this helps,Sophie
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Plantagenet Crown
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(Original post by Ezpic)
Why do they repel?
Because electrons are negatively charged, so if one negative charge meets another negative charge, there is repulsion, similar to a bar magnet.
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