please explain carbon its compound in 10th class
Answers
Carbon and its compounds:
Carbon is one of the most versatile elements in the periodic table. Our bodies are made of carbon. Your bags and water bottles are made up of carbon. The air all around you has carbon. The most metal you see has carbon in it. It is, quite literally, indispensable. Hence, carbon and its compounds are irreplaceable in our surroundings!Here are some basic facts about carbon:
Atomic Number: 6
Atomic Weight: 12
Allotropes: Atomic Carbon, graphene, graphite, diamond, amorphous carbon (as coal, soot, etc), fullerenes.
Chemical Symbol: C
Number of electrons in the valence shell
CO2 and the Carbon cycle:
CO2, also called carbon dioxide, is an essential constituent of the atmosphere, and a greenhouse gas. One of the most important among carbon and its compounds, it is essential to all life for one major reason: it is consumed by plants, which by the process of photosynthesis, use light as a catalyst to convert CO2 and water to glucose. In the process, they produce oxygen, which is used by nearly every living being that isn’t a plant.
Now, when these plants die, they get buried and can follow one of two paths. They can either act as nutrient sources for the growth of new plants, or they can get compressed over millions of years and form fossil fuels like coal. The carbon from the dead plants can enter the new, living plants, and from there into herbivores and then into carnivores. The animals too die and serve as nutrition for plants, and the cycle begins again. The fuels are consumed in factories and CO2 may be produced.
A major problem has now arisen due to the consumption of fossil fuels (which, obviously, is not a natural process). More CO2 than should exist is being produced, among other gases, and this imbalance leads to the greenhouse effect and global warming, which in turn leads to melting of ice caps and extinction of various species.
Covalent Bonding in Carbon:
Carbon and its compounds form covalent bonds which are formed by sharing of electrons among same or different molecules.
Methane: Carbon has four un-shared electrons in its valence shell. To complete its octet, carbon needs four more electrons. This is donated by four other hydrogen atoms, forming four covalent bonds.
Image result for methane
The combination of two or more non-metals results in the formation of covalent bonds.
Eg. H20(water): here, both hydrogen and oxygen are non-metals and they combine to form covalent bonds.
In molecules like carbon dioxide (CO2), the octet will not be filled if all the atoms share two electrons. If each oxygen atom shares one electron with the carbon atom, we get the following:
CO2.jpg
This way, the octet of carbon is not complete, it needs two more electrons to satisfy the octet rule. Not only is this the case with carbon, but even oxygen atoms need one more electron each in their valence shells.
Thus, to satisfy the octet rule, it is sometimes necessary for some of the molecules to share more than one electron. In this case, each oxygen atom shares two electrons and each carbon atom shares 4 electrons:
CO2 octets.jpg
In this arrangement, the carbon atom shares four electrons (two pairs) with the oxygen atom on the left and four electrons with the oxygen atom on the right. There are now eight electrons around each atom. A double bond represents a chemical bond in which two pairs of electrons are shared between two atoms:
double bond.jpg
Some molecules contain triple bonds, covalent bonds in which three pairs of electrons are shared by two atoms. A simple compound that has a triple bond is acetylene (C2H2), whose Lewis diagram is as follows:
triple bond.jpg
These are properties of covalent compounds
Melting and boiling points are low in covalent bonds.
The molecules that are bonded by covalent bonds can be separated using very less amount of energy, unlike the ions of ionic compounds that cannot be partitioned easily. Thus, covalent bonds are said to have relatively low boiling and melting points.
The enthalpy of fusion and latent heat of vapourisation is lower than those of ionic compounds.
The enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid at constant pressure. This energy includes the contribution required to make room for any associated change in volume by displacing its environment against ambient pressure. The temperature at which the phase transition occurs is the melting point.