[fishyuyue]

 In a A-level exam, one question is how many types of chemical bonds in ice ?  And the right answer is 2. I only know the covalent bond between H and O , what is the other chemical bond ?  I am confused !!!

[Borek]

http://en.wikipedia.org/wiki/Hydrogen_bond

[Alpha-Omega]

The Chemical Physics of ICE:


http://skua.gps.caltech.edu/hermann/ice.htm

[IITian]

The other one is the most common bond found in molecules having Hydrogen attached to an electronegative atom!

[fishyuyue]

thanks for your answers.
But I don't think hydrogen bond is a chemical bond. As far as I know , hydrogen bond is one type of intermolecular forces , just like temporary dipole-dipole induction and permanent dipole-dipole force.

[Alpha-Omega]

Chemical bonds are interactions of electrons leading to strong forces of attraction which holds atoms together in molecules and compounds.  Atoms may transfer or share electrons, and either process may provide for a stable arrangement of electrons between the atoms that results in the formation of molecules.

Hydrogen bonds:  In compounds such as water, ammonia (NH3), and hydrogen fluoride (HF), the hydrogen atoms are bonded to small atoms of high electronegativity (oxygen, nitrogen, and fluorine, respectively).  The hydrogen atom has only a very small share of the electron pair that forms the bond.  Such molecules are highly polar. 


In fact, each hydrogen atom acts largely as exposed proton.  It can be attracted to, and form a weak bond with, the highly electronegative atom of a neighboring molecule.  This is called a hydrogen bond.  It is more than just an electrostatic attraction between opposite charges. It actually has some covalent character.

Hydrogen bonding is responsible for a number of unusual properties.  Hydrogen bonding occurs between water molecules.  Water must be raised to a much higher temperature before the kinetic energy of its molecules becomes great enough to break the hydrogen bonds between the molecules. 

Breaking these hydrogen bonds is necessary in order to boil water.  X ray studies show that the three-dimensional structure caused by hydrogen bonding gives ice crystals a crystalline arrangement with many hexagonal openings.  This open structure accounts for the low density of ice.   


Borek and IItian have also responded accuratly and correctly.

[THC]

Chemical bonds are interactions of electrons leading to strong forces of attraction which holds atoms together in molecules and compounds.  Atoms may transfer or share electrons, and either process may provide for a stable arrangement of electrons between the atoms that results in the formation of molecules.

Hydrogen bonds:  In compounds such as water, ammonia (NH3), and hydrogen fluoride (HF), the hydrogen atoms are bonded to small atoms of high electronegativity (oxygen, nitrogen, and fluorine, respectively).  The hydrogen atom has only a very small share of the electron pair that forms the bond.  Such molecules are highly polar.  I

n fact, each hydrogen atom acts largely as exposed proton.  It can be attracted to, and form a weak bond with, the highly electronegative atom of a neighboring molecule.  This is called a hydrogen bond.  It is more than just an electrostatic attraction between opposite charges. It actually has some covalent character.

Hydrogen bonding is responsible for a number of unusual properties.  Hydrogen bonding occurs between water molecules.  Water must therefore be raised to a much higher temperature before the kinetic energy of its molecules becomes great enough to break the hydrogen bonds between the molecules.  

Breaking these hydrogen bonds is necessary in order to boil water.  X ray studies show that the three-dimensional structure caused by hydrogen bonding gives ice crystals a crystalline arrangement with many hexagonal openings.  This open structure accounts for the low density of ice.  

... from http://www.sciencebyjones.com/chemical_bonding.htm

[Alpha-Omega]

Additional References:

http://www.edinformatics.com/interactive_molecules/hydrogen_bonds.htm

http://www.aip.org/png/html/h-bond.htm

http://skua.gps.caltech.edu/hermann/ice.htm

http://www.elmhurst.edu/~chm/vchembook/161Ahydrogenbond.html

[fishyuyue]

But in CIE A-level chemistry book , the hydrogen bond is belong to intermolecular force.
BUt I read some American Chemistry book, the hydrogen bond is belong to chemical bond.
BUt in UK A-level examination, the answer needs to follow A-level chemistry booK
ANd make me confused, one A-level paper answer consider two different bonds in ice

[Alpha-Omega]

Chemical bonds are interactions of electrons leading to strong forces of attraction which holds atoms together in molecules and compounds.  Atoms may transfer or share electrons, and either process may provide for a stable arrangement of electrons between the atoms that results in the formation of molecules.

Chemical compounds are formed by the joining of two or more atoms. A stable compound occurs when the total energy of the combination has lower energy than the separated atoms. The bound state implies a net attractive force between the atoms ... a chemical bond.

The two extreme cases of chemical bonds are:

A Covalent Bond: bond in which one or more pairs of electrons are shared by two atoms.
An Ionic Bond: bond in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other.
Other types of bonds include metallic bonds and hydrogen bonding. The attractive forces between molecules in a liquid can be characterized as Van der Waals bonds.

Chemical bond, mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the formation of an aggregate with sufficient stability to be regarded as an independent species.

The number of bonds an atom forms corresponds to its valence. The amount of energy required to break a bond and produce neutral atoms is called the bond energy. All bonds arise from the attraction of unlike charges according to Coulomb's law; however, depending on the atoms involved, this force manifests itself in quite different ways. The principal types of chemical bond are the ionic, covalent, metallic, and hydrogen bonds. The ionic and covalent bonds are idealized cases, however; most bonds are of an intermediate type.

Hydrogen bonding differs from other uses of the word "bond" since it is a force of attraction between a hydrogen atom in one molecule and a small atom of high electronegativity  in another molecule. That is, it is an intermolecular force, not an intramolecular force as in the common use of the word bond.

When hydrogen atoms are joined in a polar covalent with a small atom of high electronegativity such as O, F or N, the partial positive charge on the hydrogen is highly concentrated because of its small size. If the hydrogen is close to another oxygen, fluorine or nitrogen in another molecule, then there is a force of attraction termed a dipole-dipole interaction. This attraction or "hydrogen bond" can have about 5% to 10% of the strength of a covalent bond.
Hydrogen bonding has a very important effect on the properties of water and ice.

To form water there is a chemical bond between hydrogen and oxygen.  This is a covalent bond and water is highly polar.  To make molecules a bond is either covalent or ionic.  To make one molecule of water you need 2 covalent bonds.  Two chemical bonds of O-H.  These bonds are intramolecular.

Then to stick a number of these together in a crystalline form requires intermolecular forces like hydrogen bonds.
When 2 molecules get together in a covalent/chemical bond that is what we call a dimer….water is NOT a dimer….Water molecules are held together by intermolecular forces, this is the case for all water molecules in the solid Ice) and liquid phases (liquid water).