unique nature of carbon l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Unique Nature of Carbon PowerPoint Presentation
Download Presentation
Unique Nature of Carbon

Loading in 2 Seconds...

play fullscreen
1 / 34

Unique Nature of Carbon - PowerPoint PPT Presentation


  • 384 Views
  • Uploaded on

Unique Nature of Carbon. Carbon has two properties that enable it to form such an extensive range of compounds: 1. Catenation – the ability to form chains of atoms. 2. The ability to form multiple bonds. Catenation.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Unique Nature of Carbon' - mahogony


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
unique nature of carbon
Unique Nature of Carbon

Carbon has two properties that enable it to form such an extensive range of compounds:

1. Catenation – the ability to form chains of atoms.

2. The ability to form multiple bonds.

catenation
Catenation

The elements nitrogen and oxygen do not undergo extensive catenation. Compounds that contain –O-O- bonds (peroxides) are typically unstable and explode.

Likewise, compounds containing -N-N- bonds are often explosive. An example is the azide ion, N31-.

catenation3
Catenation

Carbon readily forms long chains of bonds with itself. This property is called catenation, and is fairly unique. It results for several reasons:

1. Carbon can make up to 4 bonds.

2. The carbon-carbon bond is generally as

strong as bonds between carbon and other

elements.

3. The catenated compounds are inert.

catenation4
Catenation

Silicon can also make long chains within its compounds, but, since the silicon oxygen bond is much stronger than that between two silicon atoms, the chains typically contain –O-Si-O-Si- type links, rather than -Si-Si- bonds.

Silicon also has empty low-lying d orbitals which make its compounds more reactive.

catenation6
Catenation

Since carbon can undergo extensive catenation and make as many as four bonds, the array of compounds is limitless.

The simplest compounds, those with carbon and hydrogen, are used as the basic structure of all molecules.

carbon vs silicon8
Carbon vs. Silicon

One of the clearest differences between the two elements is in their oxides. Carbon dioxide is a non-polar molecular substance with double bonds between the carbon and the oxygens.

O=C=O

:

:

:

:

carbon vs silicon9
Carbon vs. Silicon

Since silicon doesn’t readily make double bonds, and the silicon-oxygen bond is so stable, the oxide of silicon is a network solid, in which each silicon atom is bonded to four oxygen atoms which are, in turn, bonded to other silicon atoms.

carbon vs silicon10
Carbon vs. Silicon

The oxide of silicon is found in quartz and sand.

silicates
Silicates

Silicates, ions containing silicon and oxygen, are found in most rocks, soils and clays. Their structures also are based on interconnected SiO4 tetrahedral units.

silicates12
Silicates

Glass contains silicates in a more random pattern than found in quartz.

group 5a
Group 5A

The elements of group 5A may form three, five or six covalent bonds, except for nitrogen which cannot expand its “octet.”

Due to its small size, nitrogen readily forms π bonds. Thus elemental nitrogen, N2, has a triple bond. The other elements exist as larger molecules containing single bonds.

nitrogen
Nitrogen

Elemental nitrogen is an extremely stable molecule due to the triple bond. As a result, many nitrogen containing compounds decompose exothermically (and sometimes explosively) to form nitrogen gas.

explosives
Explosives

Nitrogen based explosives such as nitroglycerin, will rapidly decompose when ignited or exposed to a sudden impact.

explosives16
Explosives

4 C3H5(NO3)3(l)  6 N2(g) + 12 CO2(g) + 10 H2O(g) + O2(g) + energy

Note the large number of moles of gaseous products. Explosives typically involve a very large volume change, producing many moles of small gaseous molecules.

explosives17
Explosives

Trinitrotoluene, TNT, is another nitrogen based explosive.

2C7H5(NO3)3(l)  12 CO2(g) + 5 H2(g) + 3N2(g) + 2C(s) + energy

sodium azide
Sodium Azide

Sodium azide, NaN3(s), is used in air bags in automobiles. A small amount of sodium azide (100g) yields 56L of nitrogen gas at 25oC and 1 atm.

sodium azide19
Sodium Azide

2 NaN3(s)  2Na(l) + 3 N2(g)

This reaction takes place in about 40ms. Other components are put in the air bag so that the molten sodium metal is deactivated into glassy silicates.

10 Na(l) +2KNO3(s) K2O(s) +5Na2O(s)+ N2(g)

2 K2O(s) + SiO2(s)  K4SiO4(s)

2 Na2O(s) + SiO2(s)  Na4SiO4(s)

isolation of phosphorus
Isolation of Phosphorus

Phosphorus was initially isolated in an attempt to extract gold from urine.

The element emits light and glows when exposed to oxygen.

phosphorus
Phosphorus

Elemental phosphorus exists as several allotropes. All differ greatly in structure from nitrogen due to a lack of multiple bonding between the larger phosphorus atoms. Phosphorous can also use d orbitals to expand its bonding.

elemental phosphorus
Elemental Phosphorus

white

phosphorus

black

phosphorus

red

phosphorus

white phosphorus
White Phosphorus

White phosphorus exists as discrete P4 molecules. It is a waxy white solid that is very poisonous and reactive. It burns vigorously in air, and is stored under water.

white phosphorus25
White Phosphorus

The element gets its name from the phosphorescent glow emitted by white phosphorus when it is exposed to air in the dark.

White phosphorus has been used in weaponry. The pieces of phosphorus in bombs and grenades get embedded in the skin, where they burn.

red phosphorus
Red Phosphorus

Red Phosphorus is a polymeric chain of P4 units. It is stable in air to a temperature of 400oC. Red phosphorus is used in “safety” matches on the striking surface.

red phosphorus27
Red Phosphorus

Red phosphorus is used in “safety” matches on the striking surface.

black phosphorus
Black Phosphorus

Black phosphorus is the most stable of the allotropes. It is formed from white phosphorus that is heated under very high pressures.

oxygen
Oxygen

Oxygen contains a double bond that is much stronger than a single bond (494 kJ/mol vs. 142 kJ/mol). The lower elements in the group form much weaker π bonds due to their larger atomic size and greater bond length.

oxygen30
Oxygen

Oxygen is a colorless, odorless gas that forms a pale blue liquid. The molecule is paramagnetic due to the presence of two unpaired electrons, and is attracted to a magnetic field.

ozone
Ozone

Ozone, O3, is an allotrope of oxygen. It occurs naturally in the upper atmosphere of earth. The ozone layer absorbs ultraviolet light and serves to help screen out harmful, cancer causing, radiation.

sulfur
Sulfur

Sulfur is found in large deposits as the free element, or in a variety of ores. Elemental sulfur has a variety of forms and structures. At room temperature, the most stable form is rhombic sulfur, S8 rings.

structure of sulfur
Structure of Sulfur

Sulfur has a tendency to bond with itself. This is called catenation. The sulfur-sulfur bonds are stable, despite lone pairs, since the bond length is relatively long.

sulfur34
Sulfur

If molten sulfur is cooled slowly, the eight- membered rings stack into monoclinic sulfur, which has a needle-like appearance.