Jquery targeting - nth-child(n)

I cut and pasted the code of Free code camp Jquery section titled:

“Target a Specific Child of an Element Using jQuery”

I added html, body and head tag and library link (Jquery, Bootstrap)
The problem is that when I open it in a browser the 2 button doesn’t bounce as in free code camp simulation.
This is the line:

$(".target:nth-child(2)").addClass(“animated bounce”);

Someone can explain me this? Probably I’m doing something wrong or I miss something.

Thanks a lot.

        $(document).ready(function() {
            $("#target1").css("color", "red");
            $("#target1").prop("disabled", true);
            $("#target1").parent().css("background-color", "red");
            $("#right-well").children().css("color", "orange");
            $(".target:nth-child(2)").addClass("animated bounce");

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
    <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
    <div class="container-fluid">
      <h3 class="text-primary text-center">jQuery Playground</h3>
      <div class="row">
        <div class="col-xs-6">
          <div class="well" id="left-well">
            <button class="btn btn-default target" id="target1">#target1</button>
            <button class="btn btn-default target" id="target2">#target2</button>
            <button class="btn btn-default target" id="target3">#target3</button>
        <div class="col-xs-6">
          <div class="well" id="right-well">
            <button class="btn btn-default target" id="target4">#target4</button>
            <button class="btn btn-default target" id="target5">#target5</button>
            <button class="btn btn-default target" id="target6">#target6</button>

Hey, the “animated bounce” thing is not standard of jQuery. You will have to include animate.css in order for this to work.