negative ion
It forms an octet / stable electronic configuration
An atom in which the outermost energy level is more than half full tends to fill its outermost energy level by adding one or more needed electrons. Such an atom forms a negative ion.
it is not right to say that " an atom form as many bonds as there are protons?" because an atom of any elemant can form bond to become stable let us take a example of oxygen it have 6 electrons in the outermost shell and to become stable it forms double covalent bond with another oxygen atom or with two hydrogen to form water it means that it forms bond with 2 electrons so in any case of any atom of any element to have 8 electrons it forms the number of bonds of the remaining electrons to form atoms.
These metal may lose two electrons.
The carbon atom is called tetravalent because it forms 4 covalent bonds. A carbon atom has a total of six electrons occupying the first two shells, i.e., the K-shell has two electrons and the L-shell has four electrons. This distribution indicates that in the outermost shell there are one completely filled 's' orbital and two half-filled 'p' orbitals, showing carbon to be a divalent atom. But in actuality, carbon displays tetravalency in the combined state. Therefore, a carbon atom has four valence electrons. It could gain four electrons to form C4- anion or lose four electrons to form C4+ cation. Both these conditions would take carbon far away from achieving stability by the octect rule. To overcome this problem carbon undergoes bonding by sharing its valence electrons. This allows it to be covalently bonded to one, two, three or four carbon atoms or atoms of other elements or groups of atoms.
The electrons (especially the valence electrons)
All forms of chemical (ionic or otherwise) involve only the valence band electrons. These electrons reside in the outermost s orbital and outermost 3 p orbitals.
Carbon has four valence electrons and to for am ionic compound, carbon should lose all the four electrons. This needs high ionisation energy and hence carbon generally shares electrons and forms covalent compounds. However carbon does form ionic compounds as in metal carbides.
ionic bond
It forms an octet / stable electronic configuration
A carbon atom has four electrons in it's outermost energy level. Most atoms become stable when their outermost energy level contains eight electrons. A carbon atom therefore readily forms four covalent bonds with the atoms of other elements.
Magnesium forms a 2+ ion by giving away its two outermost electrons.
The sharing of electrons between atoms forms a covalent bond. If electrons are donated from one atom to another to form a bond this would be an ionic bond.
Carbon forms covalent bond when it shared electrons with other atoms.
Phosphorus forms P3- ion and it has 8 valence electrons (5 valence electrons from phosphorus and three from the charge).
Carbon has four valence electrons in its outermost orbit which indicate it need four further electrons to complete its valence according to octect rule. It is also not possible for Carbon to remove all of its four valence electrons for the same cause of obeying octect rule. Hence the only option left for carbon is make covalent bonds with another carbon or any other element whose electrons are available for making a covalent bond. That's why most of the compounds of carbon are covalent.
(a) the atomic no. of carbon is 6 which means that a nutral atom of carbon contains 6 electrons .so, the electronic confugration of carbon is 2 nd 4 since a corbon atom has 4 electrons in tis outermost cell ,so it should either lose 4 electrons or gain 4 electrons to achieve the inert gas electron configuration and become stable,its not possible to remove 4 electrons from a carbon atom,its not possible to add as many as 4 electrons to a carbon atom,,therefore carbon atoms can achieve the inert gas electron arrangment only by the sharing of electrons,tthere fore ,carbon alwayz forms covalent bonds,,.