Question

Question #2efa4

Answer 1

 [Hydrogen bonds](http://socratic.org/chemistry/intermolecular-bonding/hydrogen-bonds) are [intermolecular bonds](http://socratic.org/chemistry/intermolecular-bonding/intermolecular-bonds) formed between a partially positive hydrogen in one molecule and a partially negative element in another molecule, e.g., between the H of water molecule 1 and the O of water molecule 2. 
 So when does an element become partially charged? An element becomes partially charged when it is covalently bonded to another element that is more electronegative, e.g., F, O, N, Cl. These 4 [elements](http://socratic.org/chemistry/a-first-introduction-to-matter/elements) are the MOST electronegative elements in [the periodic table](http://socratic.org/chemistry/the-periodic-table/the-periodic-table). When bonded to these elements, electron sharing is not equal, resulting to a dipole (polar) moment.
 Metals are electron donors and usually become positively-charged after donating electrons. A metallic solid's atoms are attracted to one another via a metallic bond formed by the flow of electrons from one metal atom to another.

Hope this helped!