What you need to do is set the floating of your .social-div to right. To let the wrapper still wrap all of its childs a clearfix can help:
HTML:
<div class="container">
<div class="logo"></div>
<div class="buttons"></div>
<div class="chef"></div>
<div class="social"></div>
<div style="clear:both;"></div>
</div>
CSS:
.social {
width: 200px;
height: 25px;
float:right;
margin-right:20px;
background-color: #FF0;
}