I hope this question is not too basic.
I recently edited a question and was accused of correcting a phrase that was grammatically correct to a phrase that is now wrong.
The context is:
I have Sodium and Potassium.
This type of element (i.e. elements considered to be metals)...
I changed the second sentence to
This type of elements...
because I thought there are two elements in this context.
Which of the above usage is correct? And Why?
Thanks in advance!
EDIT:
To make my question more obvious, I've made up some more complete examples:
He prepared some French fries and insomnia cookies, assuming that this type of (crispy) snacks would fit my appetite.
I am recently addicted to Triumph of Death and Tessellation; when I listen to this type of (metal) songs, I feel alive.
Is there a trusted source which claims the use of "this type of things" to be ungrammatical?
UPDATE:
Thank you all for your input. But I am more confused now.
While most of the comments seem to agree upon the same rule, some of the answers have different opinions on this. (hence downvoted?)
Could this be a preference then, where the majority of native speakers prefer not to use "this type of things"?
