what is a electron transfer?
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The movement of an electron from one place to another.
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with travelling electrons.depending on their wavelength,colours are formed
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by electrolisis\nH2O------>H2+O2\ni.e by passing electric current
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Gain one/two electron(s):\n\nIf an atom or ion acquires another electron in a chemical reaction, it has gained an electron.  ditto for two electrons.\nExample: S has 16 electrons.  If it gains one electron it becomes a S- ion.  If it gains two electrons, it becomes a S-2 ion.\n\nSteal one/two electrons:\nIf an atom or ion looses an electron in a chemical reaction, it had to go somewhere.  That "somewhere" will be to another atom/ion.  So, the receiving atom/ion could be said to have stolen the electron.  Same goes for reactions involving two electrons.\nExample: Na reacts with Cl to produce NaCl.  Cl "steals" an electron from Na, creating Na+ and a Cl- ions.\n\n"Never ever react electron"\nI have never ever heard this phrase.  Maybe it refers to a species (atom or ion) that does not participate in the reaction.  It's valence electron(s) would not react.
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The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as ultraviolet radiation or x-rays. An older term for the photoelectric effect was the Hertz effect, though this phrase has fallen out of current use.
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electron gain is considered as oxidation and electron lose is taken as reduction. and that element that give electron to other element so that it can oxidise is called as oxidizing agent\n\neg :- al^+3 -- reducing agent\n\nso here zn is getting oxidized  and ni is being redused\nNi (aq) is the redusing agent\nany doubts . mail me piyush.khadgi@gmail.com
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The electrons of the atoms in general is responsiblle for their bonding. Metal atoms are said to be "surrounded in a sea of electrons". Their electrons are loosely held together and they will be attracted to an area with a high positive charge. Electricity is the flow of electrons and when the electrons of metallic atoms get attracted they will flow thus creating electricity.
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these electrons are the ones that participate in chemical reactions, ie formation of bonds
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It is metabolism of the glucose energy by Reduction-Oxidisation (RedOx) reactions to be used in the electron transfer chain to produce Adeonsie Triphosphate (ATP) which is the basic energy unit that is used in cells.
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Water gets split and donates electrons to the chlorophyll.
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Electrons absorb energy to move from a lower level to a higher one.  They release energy going from higher to lower.
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B.  Donating electrons to photosystem II.\n\nSee discussion of water photolysis in the first source given below.\n\nAnswer A is wrong because NADPH is already reduced, and doesn't "want" any more electrons.  NADP+ is the oxidized form, which reacts with the electrons and hydrogen ions produced by the photolysis of water to form NADPH.\n\nAnswers C and D are wrong because water is an electron donor (not an electron acceptor)  in photosynthesis.  Water is photolysed, producing molecular oxygen, hydrogen ions, and electrons:\n\nH2O -> 2H+ + 2e- + 0.5O2
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Usually electrons are paired up, but sometimes you will get unpaired (single) electrons sticking out of a molecule.\n\nThese things are highly unstable and reactive because electrons like to be in pairs. Because it involves taking/losing of electrons, it is a redox reaction. When these get in our bodies they do all sorts of awful things like give you cancer :) That's why we like to eat antioxidants.
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electric current is the motion of charged particles: electrons.\n\nElectrons have a negative charge so the direction of positive current is actually the opposite direction that electrons are moving.\n\nPositive current goes from high potential to low potential--the + side of the battery to the - side of the battery.  This means in reality that electrons are flowing from the - side of the battery to the + side of the battery (opposite the current)\n\nIn order to support the motion of electons, a chemical reaction must be happening in solution that absorbs electrons at the + side and emits electrons at the - side.\n\nThis means that an oxidation occurs at the - side and a reduction occurs at the + side.\n\n(An oxidation involves electron loss and reduction involves electron gain--use the pneumonic: OIL RIG = Oxidation Is Loss, Reduction Is Gain (with respect to electrons)\n\nAlso, FYI the + side is called the cathode and the - side is called the anode.
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This is true in isolated atoms.\n\nIf we put them into the electric fields generated by nearby atoms, especially those of water of crystallisation, the energy levels can change and rearrange the electron orbitals.\n\nTo explain this to our satisfaction would mean solving the equations and getting the answers.  Unfortunately this is known as a many bodied problem and only the simplest of them can be solved.\n\nTake heart in the fact that the energy levels are so close together that we can glibly announce the fact and move on quickly to the next topic!
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The "power" in any electric current is 'voltage'.\n'Voltage' is the measure of the potential difference of electrons between two substances, and therefore the potential for electrons to be transferred between them.\nBatteries generate electricity through any one of several electrochemical reactions.  \nTwo different types of metals are placed in a catalyst (usually a liquid).  When a circuit is completed between the positive side and the negative side, electrolysis occurs - the above mentioned transferring of electrons through chemical reactions from one metal to the other.  The difference in potential felt between the  positive and negative charges (giving off an electron results in a positive charge, accepting it results in a negative charge) is again your volts.\nThe reaction continues until the battery reaches homeostasis (equilibrium, balance).\nIn some kinds of batteries applying an outside electric current properly can reverse the process - allowing you to recharge the battery.\nRechargeable batteries eventually become exhausted because of of oxidation of the polarizing metals or due to a 'memory' buildup.  'Memory' refers to a battery that is not completely discharged before it is recharged.  This is the major reason for the degradation of rechargeable battery life cycles.
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. Reading the Z-scheme\n\nWhenever molecules gain or lose electrons energy is involved. The Z-scheme is an energy diagram for electron transfer in the "light reactions" of plant photosynthesis. It applies equally well to photosynthesis by algae and cyanobacteria. The vertical energy scale shows each molecule’s ability to transfer an electron to (i.e., to reduce) the next one from left to right. The ones at the top transfer electrons easily to the ones below them, as it is a "downhill" reaction, energy-wise. However, for electron transfer from those at the bottom to those above them it is an "uphill" reaction and requires input of outside energy. The Z scheme shows the pathway of electron transfer from water to NADP+. Using this pathway, plants transform light energy into "electrical" energy (electron flow) and hence into chemical energy as reduced NADPH and ATP. Later in the "dark reactions" of photosynthesis, that chemical energy is further transformed into the chemical bonds in sugar molecules. In the complete process, carbon dioxide is joined into the sugar molecules and oxygen is released. Although it is not a structural diagram, the Z-scheme does give the sequence of electron flow (oxidation and reduction) with an energy perspective. The source of electrons is water (H2O). The large vertical red arrows represent excitation of reaction center chlorophyll molecules (by light energy) and the black arrows represent electron flow, which is downhill energy-wise. This particular version of the "Z-scheme" was developed for the novel, THE MUSIC OF SUNLIGHT by Sunlight Books in collaboration with the authors of this article.\n\nMn is the manganese center, a complex containing 4 manganese atoms, which splits two water molecules at a time into 4 protons (4H+), 4 electrons (4e-), and 2 oxygen atoms, as an oxygen molecule (O2). Tyr is a special tyrosine molecule, also sometimes referred to as Yz or simply as Z, which shuttles electrons to the "reaction center" of photosystem II (PSII). Chl P680 is the reaction center pair of chlorophyll a molecules of PSII. Excited Chl P680* has reached this state by absorbing a photon of light energy. Pheo is a pheophytin molecule, which is a chlorophyll with its central magnesium ion (Mg++) having been replaced by two hydrogens. It is the primary electron acceptor of PSII, whereas P680 is the primary electron donor. QA is a plastoquinone molecule, which is tightly bound and immovable. It is known in some circles as the primary stable electron acceptor of PSII, and it accepts and transfers one electron at a time. QB is a loosely bound plastoquinone molecule, which accepts two electrons and then takes on two protons, before it detaches and becomes mobile and called PQ. PQ is the detached plastoquinone molecule, which is mobile within the hydrophobic core of the thylakoid membrane. FeS is the Rieske iron-sulfur protein. Cyt f is cytochrome f. Cyt b6L and Cyt b6H are two cytochrome b6 molecules (of lower and higher energy). PC is plastocyanin, a highly mobile copper protein. Chl P700 and Excited Chl P700* are respectively the ground energy state and the excited energy state of the chlorophyll molecule of the "reaction center" of photosystem I. AO is a special chlorophyll a molecule that is the primary electron acceptor of PSI, whereas P700 is the primary electron donor of PSI. A1 is a phylloquinone (vitamin K) molecule. FX, FA, and FB are three separate immobile iron-sulfur protein centers. FD is ferredoxin, a somewhat mobile iron-sulfur protein. FNR is the enzyme ferredoxin-NADP oxidoreductase, which contains the active group, called FAD (flavin adenine dinucleotide). NADP+ is the oxidized form of nicotinamide adenine dinucleotide phosphate. NADPH is its reduced form.