Question

Please explain why the reactivity of the alkali metals increases as you go down group 1 but the reactivity decreases of the halogens as you go down group 7

Answer 1

Well, let's talk about group 7 first. those are the halogens F,Cl,Br,I. now if you notice, as we go down the group, the number of shells increases right? and also the atomic radius gets bigger too. as we go down the group the electronegativity goes down, because there are more electrons and they aren't as tightly held by the nucleus.

Answer 2

yes

Answer 3

Group 1:
As molecular mass, Mr increases down the group,
-valence electron is further away from necleus
-forces of attraction between necleus and valence electron decreases
-lesser energy (activation energy) needed for a reaction to take place, as in easier to donate one electron
-reactivity increases down the group

Group 7:
Down the group, Mr increases,
-since they are halogens, they acquire van der waals forces
-number of electrons increases down the group
-strength of van der waals forces increases
-forces or attraction between valence electrons and nucleus increases
-more energy(Ea) needed for a reaction to take place
-reactivity decreases down the group
(Ease of reaction/extend of reaction/rate of reaction decrease)

Answer 4

i'll be back soon

Answer 5

@zaynab123

Answer 6

@Photon336 please help so WHY does the reactivity increase as you go down group 1 but decrease as you go down group 7

Answer 7

I answered the first part, while @carolyn.x helped out on the second.

Answer 8

please sum up the answer so i can understand better

Answer 9

re-read my answer about group 7 and tell me what you don't understand, that way I can help you better.

Answer 10

ok

Answer 11

i dont quite understand the last sentence

Answer 12

alright, based on what I said what do you think the answer is in your own words

Answer 13

i think that the more electron shells it has, the harder it is for it to break?

Answer 14

Take a look at this. what happens to the atomic radius and number of shells as we go from fluorine to bromine?

Answer 15

it gets bigger

Answer 16

are there more electrons and shells?

Answer 17

yes

Answer 18

okay so the more electrons and shells we have, the electronegativity goes down. so which one of these would have the highest electronegativity and which one the lowest?

Answer 19

THE one with more electrons and shells will have less electronegativty

Answer 20

yes. and remember this is because look the nucleus is positively charged right? so the nucleus is going to hold onto the electrons because the are oppositely charged right?

so think of it like this: the more shells we have, the electrons in the outermost shells will be less tightly held by the nucleus can you see why?

Answer 21

YES

Answer 22

the farther the electrons are out, the less tightly held by the positive charge

Answer 23

so for the halogens the electronegativity goes down right, the atoms get bigger, (higher atomic radius and they become less reactive)

Answer 24

YES

Answer 25

OK I understand

Answer 26

@clamin @cutegirl @CandyCove

Answer 27

@sweetburger