Intermolecolari ties

1) Which attractive forces can be generated between more molecules:

There are 3 types of forces which totally come calls forces of van der Waals:

to) Direction dipole-dipolo electrostatic attractive Forces between 2 polar molecules that see the negative extremity of one molecule to approach itself the positive extremity of an other molecule.

b) Induzione dipole-neutra induced Viene a dipolar moment in the neutral molecule and therefore becomes one interaction dipole-dipole.

c) neutral-neutra Dispersione Forces of dispersion or London, a molecule is neutral only statistically, is in fact small dipolar moments that are generated for via of the accidental fluctuations of electronic clouds of constituent atoms. Their intensity grows with the atom number of which the molecules are formed.

2) On which physical property they go to act the intermolecolari forces:

On the latent heat of subliming or evaporation that is on the heat that must be supplied to a solid one or to a liquid in order to break off the intermolecolari ties and to make to pass it to the gaseous state. They moreover influence also the temperature of fusion that must be as well as higher how much stronger is these forces.

3) Exist intermolecolari forces for gases:

But the entity of these forces is many weak people in how much decreases with the square of the distance between two molecules.

4) Define the tie hydrogen:

It is a tie that is settled down when an atom of H is interposed between 2 atoms strongly elettronegati to you which embezzle it the electron and therefore they are approached. In such a way the distance between the 2 elettronegati atoms is smaller of that it would have been in absence of hydrogen. The force of the tie is maximum when the interposed H is placed along combining the 2 nuclei and goes as diminishing the h if it removes some. The force is however intermediate between the covalent bond and the forces of van der Waals.

5) Illustrate the tie hydrogen in the water and its consequences on the property of the same water:

In the water the hydrogen acts as from bridge between 2 molecules of Or, in fact everyone of the 2 H of the molecule of ₂HOr alloy to one of the 2 doppietti solitary of an other Or pertaining to a second water molecule, totally therefore every water molecule is connected to others 4 water molecules. To notice that the length of the 2 covalenti ties will be inferior to the length of the 2 ties hydrogen.

6) As it is explained that the ice floats on the water:

The liquid water is mainly dense regarding the ice in how much the ice being a tidy structure forms n° maximum of ties hydrogen, what that not ago instead the liquid water whose molecules therefore have way to compattarsi mainly.

Ionian molecule structures and

7) Describe the theory of the repulsion between the electron braces of the layer of valence VSEPR:

The electron braces on the valence layer reject in how much all charges negatively and the smaller state of energy and therefore the maximum stability obtains when they based on their force (tied to the distance from the nucleus) is offered so as to to balance the forze.È to notice that a solitary brace being nearer the nucleus rejects with greater force the braces of tie of how much these does not make between they. In particular:

2 braces of tie 180 ° molecule lineare BeH₂

3 braces of legame 120 ° molecule trigonale BF₃

4 braces of legame 109,5 ° molecule tetraedrica CH₄

3 braces of tie 1 lone pair 107 ° trigonale molecule piramidale NH₃

3 braces of tie 2 lone pairs 104,5 ° tetrahedral molecule H₂Or

8) Describe the linear molecules and to make of an example:

In linear molecules, all the atoms giacciono on one straight. An example is the hydrochloric acid HCl where a single covalent bond between the chlorine of 7° the group and hydrogen of 1° the group is present.

9) Describe the triatomiche molecules angle irons and to make of an example:

In these molecules the atoms are not found on a straight one and therefore the ties form a various angle from 180°.

A triatomica molecule example is the water H₂Or in which oxygen has on the more external layer solitary 2 doppietti (lone pair) and two electrons it disappears to you, these last ones form covalenti ties with the H, the ties therefore you form to you but they are rejected between they in smaller measure of how much instead reject between they the 2 doppietti solitary, therefore between the 2 previewed ties there is an angle of 105° against the 109,5° for a tetraedro.

10) Describe the trigonali flat molecules and to make of an example:

In they are present 4 atoms, arranged all on a same one slowly, of which it is found to the center of an equilateral triangle on whose you concern are the others 3. An example is the trifluoruro of boron BF₃ where one is had hybridization for resonance of the fluorine, due to the strong difference of elettronegatività of the 2 elements.

11) Describe pyramidal the trigonali molecules and to make of an example:

In they are present 4 atoms, arranged to shape of pyramid with triangular base.

An example is ammonia NH₃ in which the nitrogen of 5° the group is found to the center of the pyramid, it has on the more external layer 1 doppietto hermit and 3 electrons isolate to you, these form 3 ties with as many atoms of H, however doppietto the hermit finds more neighbor to the nucleus and therefore she will reject with greater energy the formed ties, therefore the angle between the ties is not of 109,5° but of 107° and the pyramid that the hermit to the apex sees doppietto it is therefore steeper than how much it would have been in absence of the doppietto.

12) Describe the tetrahedral molecules and to make of an example:

They are constituted from 5 atoms of which 4 are found to concern of a tetrahedron (pyramid to us to base triangular ) and fifth if it finds some to the center. An example is methane CH₄ where carbon C of 4° the group is found to the center and for via of the insufficient difference of elettronegatività form covalenti ties with the H which between they has an angle of 109,5° to confirmation of the insufficient polarity of the tie.

13) Describe the trigonali bipyramidal molecules and to make of an example:

In they 6 atoms are present, of which 5 disposed ones to you concern us of one trigonale bipyramid and 6° the atom to the center.

An example is the pentafluoruro of phosphorus, PF₅ in which the P phosphorus of 5° the group, it is found to the center and forms 5 covalenti ties with the fluorine of which those equatorial ones (slowly on which they are the bases of the 2 the pyramids) they are shorter regarding that axial (straight containing center of the bipyramid and the 2 you concern to us).

14) Describe the octahedral molecules and to make of an example:

In they 7 atoms are present, of which 6 disposed ones to you concern and one to us to the center of an octahedron (quadrangular bipyramid to base). An example is the sulfur fluorine SF₆ where atom S a sulfur of 6° the group finds to the center and alloy with covalenti ties to 6 atoms of F, decided to you concern us of the octahedron.

15) Describe the molecules to delocalizzati electrons and to make of an example:

In they some of tie electrons are not localize to you in the space between 2 adjacent atoms but they occupy orbital that extend to one immense region of the molecule.

An example classic is benzene C₆H₆ where every carbon atom C that is one element of 4° the group, it uses 1 spaiato electron in order to tie itself to an atom of H, and 3 electrons in order to tie itself to two atoms of C.

It could be assumed that every C forms 3 ties, 2 towards one 1° C and 1 towards one 2° C, but the molecule in the complex sees the C to form a hexagon from regular sides and therefore, follows that all the ties must be equal that other C is explained asserting every C forms a single tie with 2, but the ties are strengthen to you from 6 delocalizzati electrons.