Grammar usage of "と、～た"


I'm not completely sure on the grammar usage of と、～た, in these following
sentences, but have been given the general explanation that the imply an
unexpected result following a normal (one time?) action.

１．弟は昼ごはんを食べると、片付けもせずに出かけてしまった。

２．私が「ごめん」と言うと、友達は「あやまるのはぼくのほうだ」と言った。

I'm also unsure of how to translate と as it applies to the first half of the
sentence in these cases either, or the tense.




「と」は接続助詞といいます。  
It is a connective particle.

> １．弟は昼ごはんを食べると、片付けもせずに出かけてしまった。  
>  ２．私が「ごめん」と言うと、友達は「あやまるのはぼくのほうだ」と言った。

In these phrases, the connective particle "shows at the opportunity when a
certain situation happens or an opportunity to notice it."

  * When my younger brother finished eating lunch, he has gone out without clearing the table. 

  * When I said "I'm sorry," my friend said "It's me that should apologize to you."

