$(".alan").mouseover(function(){
$(this).css("background",red);
})
<!DOCTYPE html>
<html lang="en">
<head>
<title>cArleone</title>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<script type="text/javascript">
$(function(){
$(".alan").mouseover(function(){
$(this).hide(1000);
})
})
</script>
<style type="text/css">
.alan{width:100px;height:100px;background:red;}
</style>
</head>
<body>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
<div class="alan">cArleone</div>
</body>
</html>