そんな used in disbelief


I know that そんな means "like that", but as I read more and more mangas, I get
the feeling that it is also used as an expression of disbelief. Can someone
elaborate and do similar words like こんな or どんな have similar use in this case?




そんな itself means "such" when it's used before a noun or to refer to the amount
you are seeing when used as そんなに. So, yes, it can be used as an expression of
disbelief.

Some examples:

> そんなに食べるの？？？

Are you going to eat that much??? (You see lots of food in front of the person
and you can't believe that the person is trying to each that amount of food.)

> こんなに食べたの？？？

Did you eat all of them??? (You see lots of empty plates in front of the
person and you can't believe that the person ate all of it.)

> そんな（ばかな／きたない）ことしないで

Don't do such a (stupid/dirty) thing

> そんな（ばかな／つめたい／ひどい）こと言わないで

Don't say such a (stupid/cold/cruel) thing

So, taking @NothingAtAll's advice...  
You may hear people say `そんな。。。`, which has the nuance of disbelief because
you are just not repeating or describing the details (ellipsis of the above
examples), and it kind of means like `Oh no...` by itself

Examples:

> A: You are the worst student I've ever had
>
> B: そんな。。。 （そんなひどいこと言うのね。。。）

or

> A: You are not allowed to join the party!
>
> B: そんな。。。(そんなひどいことを私にするのね。。。）




そんな itself means "such" when it's used before a noun or to refer to the amount
you are seeing when used as そんなに. So, yes, it can be used as an expression of
disbelief.

Some examples:

> そんなに食べるの？？？

Are you going to eat that much??? (You see lots of food in front of the person
and you can't believe that the person is trying to each that amount of food.)

> こんなに食べたの？？？

Did you eat all of them??? (You see lots of empty plates in front of the
person and you can't believe that the person ate all of it.)

> そんな（ばかな／きたない）ことしないで

Don't do such a (stupid/dirty) thing

> そんな（ばかな／つめたい／ひどい）こと言わないで

Don't say such a (stupid/cold/cruel) thing

So, taking @NothingAtAll's advice...  
You may hear people say `そんな。。。`, which has the nuance of disbelief because
you are just not repeating or describing the details (ellipsis of the above
examples), and it kind of means like `Oh no...` by itself

Examples:

> A: You are the worst student I've ever had
>
> B: そんな。。。 （そんなひどいこと言うのね。。。）

or

> A: You are not allowed to join the party!
>
> B: そんな。。。(そんなひどいことを私にするのね。。。）

