Why do atoms react, and how?
Atoms having eight electrons in their last orbit are stable and have no tendency to react. Atoms having less than eight electrons then react with other atoms to get eight electrons in their outermost orbit and become stable. Atoms having slightly excess than eight electrons may lose them to atoms which are short of eight. Atoms that cannot either lose or gain may share to get octet configuration. Molecules short of octet configuration, even after the reaction, may accept lone pairs of electrons present in other atoms or molecules.
Name the forces that keep reacting atoms together.
In metals, the outer orbitals of atoms overlap, and so the electrons present in them do not belong to any particular atom but flow over to all atoms, as well and bind them all together (metallic bonding). Atoms that have to lose and gain electrons become ions and are held together by the electrostatic forces of attraction (ionic bond). When atoms equally give and share electrons, the shared electrons become the unifying force between them (covalent bond). Electron-deficient and free lone pair-containing molecules may again and satisfy the octet thirst of the electron-deficient atom. The shared electron bridges the electron-rich atom with the electron-deficient atom (coordinate bond).
What are hybridized orbitals? What are their uses?
Relatively similar energy sub-orbitals may merge and form a new set of the same number of orbitals, having the property of all the contributing orbitals in proportion to their numbers. These orbitals are hybridized orbitals. They are useful in explaining the similarity in bond length, bond angles, structure, shape and magnetic properties of molecules.
sp3 and dsp2 are four hybridized orbitals. But one is a tetrahedral shape, and the other is square planar. Why?
sp3 orbitals are formed from the s -subshell with uniform electron distribution around the nucleus and from the p-subshell with distribution in the three vertical axes. Hybridized orbitals, hence have their electron distribution in three dimensions, as tetrahedral directions.
In dsp2, all the orbitals involved in hybridization have their electron distribution around the same plane. Hence, the hybridized orbitals also are in the same plane giving rise to square planar geometry.
The oxygen molecule is paramagnetic. Is there an explanation?
An oxygen atom shares two electrons, each with another oxygen atom, to form the oxygen molecule. Oxygen molecule exhibits paramagnetic nature indicating unpaired electrons. A molecular orbital theory has been proposed to explain this. According to this theory, atoms lose their orbitals and rather form an equal number of orbitals covering the entire molecule and hence, the name molecular orbital. Filling up of these orbitals in increasing energy order leaves unpaired electrons explaining the paramagnetic behaviour of oxygen molecules.
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