water liquidity , why at room temp. ?

Discussion in 'Chemistry' started by river, Aug 29, 2011.

  1. Aqueous Id flat Earth skeptic Valued Senior Member

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    The chemical explanation for the liquid phase of any compound is that it is specific to that compound. Water has a specific melting and boiling point, as does iron, or oxygen in the air, or any other simple compound you name. The fact that a compound (H20) contains given elements from other compounds (O2 and H2) has no relation to the properties, such as boiling and freezing point. Properties of materials are generally related to physical qualities of the individual molecules, for example, molecular diameter, polarity, and geometric structure. Since the physical attributes of H20 are very different from O2 and H2, the properties, such as melting point, are also different.
     
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  3. Nasor Valued Senior Member

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    It is always energetically favorable for a free electron to add itself to a cation or neutral atom. Often it is energetically favorable for an electron to add itself to anions. The reason has to do with how well the electrons that are already present are able to shield an incoming additional electron from the positive charge of the nucleus. Specifically, electrons don't shield other electrons in the same subshell very well, but they shield well against electrons with higher principle quantum numbers. This is why an electron that approaches a O- anions will still be electrostatically attracted, even though the overall charge is already negative. As for not seeing a lot of K- anions floating around, that's because the reduction potential of potassium is really low. Just because it's energetically favorable for a neutral potassium atom to combine with an electron to make a K- anion, that doesn't mean it won't be even more favorable for the electron to be stolen by the first thing to come along with a higher reduction potential.
     
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  5. wellwisher Banned Banned

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    You coud also use the concept of electro negativity which measures an elements affiinty for electrons. If we react magnesium and oxygen atoms, we get magnesium oxide. They both start out as neutral atoms, with equal number of protons and electons, but the magnesium ends up Mg+2 and the oxygen as O-2. Although electro negativity tells us this will happen it does not tell us how. Why does one atom end up with less electrons and the other more electrons when both start neutral. The only forces at work is the EM force, so that need to be part of the explanation.
     
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  7. Nasor Valued Senior Member

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    You are basically asking why various atoms and ions have the reduction potential that they do. The answer to this question typically fills at least one chapter in an inorganic or physical chemistry textbook, and I don't feel like writing a long essay on the subject. If you really want to know, I can recommend specific textbooks and pages.

    For the most part, though, it has to do with how well the electrons that are already present shield new, incoming electrons from the positive charge of the nucleus and the size of the atom (which determines how close additional electrons can get to the nucleus, and thus how much electrostatic attraction they experience). Magnetic interactions are present, but they have very little influence in most cases, and the amount of energy involved in the magnetic exchanges is pretty trivial compared to the electrostatic energies, at least until you start to consider really big atoms with lots of d and f electrons. Such big atoms can have lots of electrons in the same subshell, which provides lots of opportunity for magnetic interactions with other electrons in the same sub-shell, and have valence electrons relatively far away from the nucleus, so electrostatic effects are lessened.
     
  8. Trippy ALEA IACTA EST Staff Member

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    The short answer, and what, I believe, Nasor is trying to say is that you've answered your own question, you just need to look a little closer at what electronegativity is, what it means, and how it varies across each row.

    I'll give you a clue though, it has to do with electrostatic shielding, and the fact that from the presepective of a 2s or 2p orbital, a 1s electron has greater effective shielding than another 2s or another 2d electron (the implication of which is that as you move across a row, valence electrons see an increasing effective nuclear charge, and so become more strongly bound to the nucleus).
     
  9. river Valued Senior Member

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    guys

    I don't see how all this chemical explaination , explains how particles , atoms , have both particle and fluid properties

    so far you have expaining the interactions between the elements , hydrogen and oxygen

    but where does the state of liquid come from

    is it from the distance or the space between the electron and the proton ?
     
  10. Nasor Valued Senior Member

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    I don't think he has answered his own question; he's talking about magnetism and electromagnets. Rather than electronegativity, I would suggest looking up electron affinity and how it relates to Slater's rules and reduction potential (for him, I mean; you already appear to understand it).
     
  11. origin Trump is the best argument against a democracy. Valued Senior Member

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    No, lets look at water for an example. In the solid state (ice) the water molecules are immobile (there is vibration but they are not moving out of the crystal lattice) and bound together in a crystal lattice. As energy is added to the ice the molecules begin to vibrate more and more (translational vibration energy is temperature). At a certain point (0 C) the vibrational energy is high enough that the molecules 'shake' loose from the crystal the molecules are then moving around and no longer bound in a crystal - this is the liquid state. As more energy is added to the water at 100C and 1 atmosphere, there is enough vibratonal energy that the molecules are able to leave the liquid and move into the air this is the gas phase or steam.
     
    Last edited: Nov 4, 2011
  12. river Valued Senior Member

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    9,182



    your looking at the molecule reactions to heat

    fine , we now that ice , to water , requires heat

    however , try to think of what I'm trying to get across

    you have two atoms that become liquid a room temps.

    but separated , become liquid at very low temps. -256 for oxygen and -276 or so for hydrogen

    the reasons why aren't so important to me as the manifestation of the form , liquid state

    you have three atoms , which are physical , in form , and have solid cores , that manifest a liquid state
     
  13. Trippy ALEA IACTA EST Staff Member

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    Actually, for a long time, the leading model of nuclear properties was the liquid drop model, it essentially treated the nucleus of an atom as an incompressible fluid, complete with surface tension. It made a number of successful predictions regarding nuclear properties (for example, shape, and binding energy) but failed to predict phenomena such as 'magic numbers' and 'islands of stability' (isotopes with unusually long half lives, best explained if the nucleus behaves as if it has shells, or energy levels).

    Having said that, the physical properties of the bulk substance are not dependent upon the way the nucleus is described.

    The physical properties of the bulk substance are governed by how heavy the atoms or molecules are, how much space they take up, and how that space is arranged, and the electrostatic interactions between the atoms and molecules that make up the bulk substance.

    A liquid is basicaly just a solid with constituent particles that have sufficient energy to partially, but not completely overcome the attraction between its constiuent particles.

    Some portion have sufficient energy to overcome this attraction - which we call surface tension, and manage to escape if they're near a boundary and able to do so. We call this vapour pressure, and it leads to evaporation.

    The precise physical properties of the bulk liquid are determined by the electrostatic attraction between particles, how heavy the particles are, and how easily the particles can become physicaly entangled with one another.

    I'm not sure how to put it any simpler than that.
     
  14. river Valued Senior Member

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    9,182

    very good really

    it was very stimulating

    this is the kind of depth I've been looking for , for a very long , long , time
     
    Last edited: Nov 8, 2011
  15. wellwisher Banned Banned

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    Electrostatic forces alone, can not explain physical properties of atoms and molecules since this can not explain why different atoms have different affinities for the electrons needed to balance their positive charge. For example, oxygen is stable as oxide or O-2 while hydrogen can exist as H+.

    The entire story requires the electromagnetic force which is a composite force with both electrostatic and magnetic attributes. A magnetic field will form when a charge is in motion. A stationary charge will only have an electrostatic force. But since electrons are not stationary on atoms, but in constant motion in orbitals, orbital electrons are charges in motion thereby creating a magnetic field in conjunction with their electrostatic force.

    Magnetic fields follow the right hand rule. The magnetic field will form perpendicular to the direction of the motion of the charge. Perpendicular to these two vectors will be the magnetic force vector. The result looks like (x,y,z). Opposite spin or opposite direction electrons will have their force vectors orientated so these will have an attractive force.

    Even though stationary electrons would repel via the electrostatic force, when they are in motion, in the shape of an orbital they create a magnetic field. If the motion allows their magnetic force vectors to attract this attraction can be stronger than the electrostatic repulsion.

    In the case of O-2, the electrostatic charge would like to form neutral O atoms, but the orientation of the electrons in the P-oribitals and the direction of motion creates powerful magnetic attraction that is so strong O can hold two extra electrons. This unique orientation of the EM force vectors in the orbitals of O makes O the most important terminal electron acceptor on the earth.

    One source of misunderstanding is comparing the theory to the measured magnetic fields of atoms. This magnet field is very weak, with this weakness reflecting the efficiency of the magnetic attraction. For example, if we had a positive and negative stationary charge they both give off fields but since they are opposite they will attract and the fields will appear to cancel. At a distance it will appear neutral with no net charge field, but up close we see two opposite fields. The magnetic fields up close will look opposite, but at a distance they can appear neutral. Magnetic iron has a strong net magnetic field due to inefficiency in magnetic field attractions due to single electrons in orbitals.
     
    Last edited: Nov 8, 2011
  16. hardalee Registered Senior Member

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    341
    The laws of physics as being discussed in this thread require that water be a liquid at our “room temperature”.

    If water was not a liquid at room temperature, we would not be around to ask the question. There would be no life, or more specifically, no life like us.

    Also, if water, unlike other liquids, did not expand as became frozen and float rather than sink, we would also not be around to ask questions.

    These two reasons, likely amongst others, are why we look for liquid water as one of the requirements of life on other planets.

    If the multiverse and landscape theories are correct, there may be many other places with different physics that would or would not allow life forms who can ask questions.
     
  17. wellwisher Banned Banned

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    5,160
    Water is a liquid at room temperature because of oxygen's strong affinity for electrons. The shared electrons between the hydrogen and oxygen within water tend to reside closer to the oxygen atoms, even though this makes the oxygen negative and hydrogen positive. Again, it has to do with the EM force and moving charges within orbital shapes.

    This dipole contains some residual potential energy with further lowering of energy possible if neighboring water molecules attract their opposite charges. This is called hydrogen bonding. This secondary bonding allows the small water molecule to be liquid at room temperature.

    Water will expand when it freezes. The reason this occurs also helps explain why water is liquid at room temperature. Water expands when it freezes because hydrogen bonding, between water molecules, has partial covalent bonding character. The orbitals between neighboring water molecules can overlap better if they are at certain distance. This causes ice to expand. This sweet distance brings the magnetic force back into the picture, making the bond stronger even though the water molecules are farther away.

    In liquid water, there are both high and low density domaines, which are like zone of denser and less dense water. The lower density is similar to expanded water or liquid ice, where the hydrogen bonds stretch for more covalent character. Although expanded these are help tightly. The higher density water domains have the water molecules closer, but since it is not in the sweet spot for optimize partial covalent bonding, these water molecules can evaporate easier. They mostly use van der Waals and polar bonds. But since these high and low density water domaines swap back and forth water remains a liquid with surface tension.

    Because oxygen holds the electrons in water so tight, there are other effects that are created, which are needed for life. One very important is the pH effect. Oxygen can hold the shared electrons in water tight enough for H+ to leave for another water molecules and form OH-. This self ionization is very important, with not all solvent able to do this in concentrations needed for life.

    One spin off from oxygen's strong affinity for electrons and dissociated hydrogen protons, are the hydrogen proton can be made to move in currents within water, with the hydrogen proton the fastest thing in water. It will jump from water to water and beat anything to the other side. In cells, before molecules reach their goal, H+ is already there making preparations, since all movement in water is hydrated creating potential within the water domaines and impacting how the H+ of pH is able to become integrated in the hydration or not.
     
  18. Nasor Valued Senior Member

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    6,221
    Yes, they can. The fact that no one here cares to write out a detailed, multi-page explanation of something that can be found in plenty of undergrad textbooks doesn't mean that the explanation doesn't exist; it just means that you're too lazy to look it up.
    No. I'm trying to be polite here, but you don't appear to have even a highschool-level understanding of atomic orbitals or electron configurations. I have to ask, what is the highest level of education you've attained in chemistry or physics?
     
  19. Trippy ALEA IACTA EST Staff Member

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    Yes they can, and the explanation, or at least, a greatly simplified version of it, has been given in this thread already.

    Core electrons shield nuclear charge more effectively than valence electrons.

    As you move along a row of the periodic table, you add protons and electrons to your atoms. The electrons you add are valence electrons, therefore as you move across the row, the effective nuclear charge felt by each electron increases.

    This is sufficient to explain why Lithium and Berylium are so keen to shed their electrons, but Oxygen and Fluorine are so keen to take them - because the valence electrons of Oxygen are more strongly attracted to the nucleus, then the valence electrons of Berylium (well, more or less).

    Seconded. I came across this as a logical fallacy. Its name, however, elludes me. I think it's something very similar to 'No simple answer'.
     
  20. river Valued Senior Member

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    9,182
    guys couln't be that water is a quantum energy form

    so that things in the quantum world also burn , in combinations , as they do in the macro world

    so that water is a quatum energy state ?
     
  21. river Valued Senior Member

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    I have never come across this discussion ..... anywhere
     
  22. river Valued Senior Member

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    look

    radium , is a brillant white metallic element

    it gives off , gas , radon

    now Radon is a real gas beause it has to ventilated In mining shafts of uranium and its a Heavy radioactive gaseous element formed by the decay of radium

    so we have this element , radium , in decay , which gives of a heavy gas , radon
     
    Last edited: Nov 9, 2011
  23. river Valued Senior Member

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    9,182
    just for interests sake

    radium emits alpha particles and gamma rays

    so radium has a way of capturing both types of energy
     

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