CARBON HYBRIDIZATION sp3

CARBON HYBRIDIZATION sp3

To talk about hybridization in Carbon we need to remember that this element Atomic Number is 6, then its electron configuration is

    \[ 1s^2, 2s^2, 2p^2 \]

Which we can represent also using the spin sign of the electrons

    \[ 1s^{\uparrow}^{\downarrow}, 2s^{\uparrow}^{\downarrow}, 2p^{\uparrow}^{\downarrow} \]

The Electrons who participate in Hybridization are those in level 2

2 electrons in sub level ‘s’ , 2 electrons in sub level ‘p’. Since ‘p’ has 3 orientations, ‘px’, ‘py’ and ‘pz’, and we have just 2 electrons, ‘pz’ will remain empty at this moment

    \[ 2s^{\uparrow}^{\downarrow}  2px ^{\uparrow} 2py^{\uparrow} 2pz \]

Carbon solves this situation sending 1 electron from orbital ‘s’ to orbital ‘pz’, and when that happens, the orbitals take a new Name, and a new Form, they become Orbitals ‘sp’

    \[ 2sp^{\uparrow}  2sp ^{\uparrow} 2sp^{\uparrow} 2sp^{\uparrow} \]

Hybridization is mixing atomic orbitals into new Hybrid Orbitals

We get 4 new Hybrid Orbitals, and they are called more specifically ‘sp3’, because they were created mixing 1 ‘s’ orbital with 3 ‘p’ orbitals.

The angle among these new orbitals is 109.5 degrees.

Carbon use this orbitals when creates single bonding molecules, for example with Hydrogen, which has 1 electron, they will complete one orbital ‘sp’ with 2 electrons.

If one Carbon is combined with 4 Hydrogens, will build a molecule of Methane,

    \[ CH_4 \]

in that case the final electronic distribution for level 2 will be

    \[ 2sp^{\uparrow}^{\downarrow}  2sp ^{\uparrow}^{\downarrow} 2sp^{\uparrow \downarrow} 2sp^{\uparrow \downarrow} \]

and Carbon reaches stability because now has 8 electrons in its valence shell.

 

CARBON and ORGANIC CHEMISTRY

We are going to use the Periodic Table to talk about a very important element, which is Carbon, one of the stars of modern chemistry because is present in almost every compound  around us. Carbon itself is the principal protagonist of the part of Chemistry called Organic Chemistry.

 

Carbon is located in Group 4A of the Periodic Table of the Elements, that means this Element will be forming compounds sharing until 4 electrons.

Carbon and Organic Chemistry are present in different kind of materials for example in paints, rubbers, oils (and all petrochemical derivates), plastics (polymers of carbon), and even in Steel forming alloys with  metals.

In live organisms Carbon is part of the skin, hair, blood (as amino acids and proteins), fats (or lipids), carbohydrates such us glucose, DNA, RNA, vitamins, and carbon dioxide, that is why is important for Pharmaceutical  and Food industries.

Carbon is also present in graphites (as in pencils) and diamonds.

Organic Chemistry is based in an element called Carbon.

How Carbon is present in all different compounds?

There are two principal characteristic of this Element, that make him different and special from other Elements:

1st) When form compounds, they share electrons, that means that they don’t take or give electrons (they do not create ionic bonding). They form covalent bondings

2nd) They are able to share until 4 electrons. Most Elements win or take less than 3 electrons.

Now, we’ll try to see How Carbon creates compounds

We know that Carbon has 4 electrons in its valence shell, these electrons are in orbitals, one electron in one orbital.

The orbitals are around Carbon, not forming 90º or 180º  among them, but 109.5º in all cases.

To complete each orbital we need 1 electron, that can be provided for an Hydrogen for example. If that is the case, one Carbon will need 4 Hydrogens, and the final molecule is Methane, CH4.

A better representation of, methane, is this. One Carbon surrounded by 4 Hydrogens at the same distance and same angle among them.

When Carbon wants to create a bigger molecule, it replaces one Hydrogen for another Carbon and complete the other bondings with other atoms, as Hydrogens or another Carbon.

For example, when in a molecule we have 3 Carbons, then we will need 8 Hydrogens, and in that case the molecule is called Propane.

SOLUTIONS PREPARATION 1

Today we’ll start to talk about how to prepare a solution. We need to remember that solutions are formed mixing a solute, which is usually a solid, for example sodium chloride, and a Solvent which is usually water.

To measure water we use special materials as beakers and graduated cylinders, but  they just give us an approximate amount of liquid, so even when they have scales about the amount that we are measuring with them, they are not exact.

Volumetric Flasks, give us an exact amount of liquid, and when we prepare solutions they represent the final amount of the solution, as for example 100 mL or 25 mL.

When we finish preparing the solutions, we storage them. We label these bottles with the Concentration, name, date and MSDS code for the solution. Most of the storage bottles are made of glass but some solutions require plastic materials, as for example Sodium Hydroxide or Hydrofluoric acid solutions.

 

DISSOLUTION

It is the process by which a solute (solid, liquid or gaseous) in contact with a solvent is dispersed forming a mixture in which the components are not distinguishable. The best example of a solution is a salt dissolved in water, the most common salt is the one we use every day at the table by the time we eat, this salt has a crystal form, is composed of ions sodium positively charged, and ions chloride with negative charge.

When a salt crystal is in contact with big amount of water, ions Chloride, negative charged, will be attracted by the positive side of water which are the hydrogen atoms, they take the ions from the crystal lattice, and the original solid pass to same state of the solvent.
The final mix is homogeneous and have the same properties in the whole mix.

In Chemistry is important to know the amount of solute in a solution, this value is known as Concentration of the solution. The concentration of a solution is calculated using

Concentration\text{ of Solution = }\tfrac{Amount\text{ }of\text{ Solute}}{Amount\text{ of Solute + Amount of Solvent}}

Example:
Molarity\text{ = }\tfrac{Moles\text{ }of\text{ Solute}}{Volume\text{ of Solution}}

Next chapter will show different ways to express concentration of solutions.

WATER POLARITY

Water is one of the most important molecules in human life, not only because makes up more than two thirds of human body weight, but also because all the cell and organ functions depend on water for their functioning. Something similar occurs in animals and plants. This means that without water most kind of life on earth would disappear in a few days.

Water is composed of one Oxygen atom and two Hydrogen atoms. Oxygen has six electrons in its valence shell, and needs two electrons to acquire great stability, those two electrons are taken from two Hydrogen atoms.

The molecule of H2O is a three dimensional structure, Oxygen is the centre of the molecule, around him there are two pairs of electrons, and two Hydrogen atoms with angles around 107º among them.

Polarity

Oxygen and Hydrogen have electronegativity values of  3.5 and 2.1 respectively, when they are bonded the shared electrons are attracted to the Oxygen side, leaving the Hydrogen atoms with a slightly positive charge, and producing a final polar molecule.

When a water molecule is surrounded by another water molecule, they will interact each other through those slight charges. This interaction is called “Hydrogen Bonding”, which is a weak electrostatic attraction between slight positive and negative charges of different molecules.

NON-POLAR BOND

In a Non polar Covalent Bond, atoms share their electrons equally. That happens when, they have the same electronegativity or the same electron affinity. The best examples for this  kind of bonds are molecules created through the union of atoms of the same element, as in H2, N2, O2, Cl2  

When non-polar molecules interact among them, there are negligible forces of attraction, and they remain as individual molecules, that means these substances are gases.

In our environment we have these substances in the Air, which has approximately the following composition, 78% of N2, 21% of O2, 0.9% Ar (noble gas)

 

 

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