Co-ordinate bond is type of bond which is formed between two atoms in which one atom completely donates its two electron or one lone pair to second atom. What we usually see in covalent bond is that in covalent bond 1 electron is shared by one atom and the another electron is shared by II atom, so in covalent bond there is sharing of electrons. But in co-ordinate bond, the two electrons come from single atom which is called donor atom(as it donates its lone pair) and the atom to which lone pairs are donated , or we can say the atom which is receiving electrons or lone pair is known as receiver atom. Now the question arises that oxygen has 6 electrons and if it gets two more electrons, then its octet will be completed and it will become stable. During the formation of a co-ordinate bond the donor atom donates two electrons which suggests that the donor atom has two free electrons which are not involved with any other atom in bond i.e., they are just free to use. So why ...
The brain has possibly 100 billion neurons, each of which connects to up to 10,000 (typically) other neurons. By some estimates, there are over 100 trillion total connection points or "synapses" in the human brain. As information flows through the neural circuits and networks of the brain, the activity of the neurons causes the connection points to become stronger or weaker in response. Our brain encodes memories by altering or changing the strength of synapses(synaptic plasticity), or connections between neurons. The mechanism behind this is called "long-term potentiation" or "LTP" This requires interactions of many proteins found in both presynaptic neurons, which send information about an event, and postsynaptic neurons, which receive the information. By strengthening and weakening the connections between synapses(the terminal of neuron) our brain stores information(memories). Now the question is how our brain strengthens and weakens connections between...
Why does SF6 exist whereas SH6 does not? First of all, the order of increasing in electronegativites of Hydrogen, Sulfur and Fluorine is: H (2.2) < S (2.6) < F (4.0) Therefore, in SF6 you can imagine, F is “oxidizing” S so S atom exhibits a positive oxidation state, which is +6 in this case. However, when H and S are present things reverse: S is “oxidizing” H so H atom exhibits a positive oxidation state of +1 (the only way), and S atom is in its lowest, -2, oxidation state. This corresponds to a widely known compound, H2S, not SH6. Viewing SH6 as S (+6) and H (-1) makes things even worse. Each of the atoms is at its “critical” oxidation state for S (+6) is powerfully oxidative and H (-1) is powerfully reductive (clarified thanks to Lukasz Golon), so one could imagine a drastic intramolecular oxidation-reduction reaction to take place, with H (-1) reducing S (+6). This is another reason why SH6 does not exist. Moreover, the existence of SF6 also depends on the sizes of the atoms....
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