Metals Definition and 340 Threads

Why electrical current is possible only with the presence of energy BANDs, rather than discrete energy levels. Thank you.

It is my understanding that metals are a crystal lattice of ions, held together by delocalized electrons, which move freely through the lattice (and conduct electricity, heat, etc.). If two pieces of the same metal are touched together, why don't they bond? It seems to me the delocalized...

Hi Admin, please allow me to post this here: The General Formula for Specific Heat Capacity is: C(Total) = C(electron)+C(phonon) C(electron) = aT where a is the sommerfield constant. C(phonon) = bT^3 this time i don't know what is b (some constant) so my problem is, how can i determine b...

I asked this in another thread and was told this question should have had its own thread so as to not hijack the other thread. That question was: Has anyone calculated how much if any gold is produced in the sun? which is likely almost none do to the differences between fusion and fission and...

A structure with free electron density around 10^26 m^-3 is considered as a highly doped semiconductor or a metal? Or in other words, what is the lowest possible free electron concentration for a metal and what is the highest possible free electron concentration for a doped semiconductor?

Hi, please could someone explain why silver is a better conductor than, say, copper. Is it due to the fact that it has more conduction electrons than copper? I can't seem to find a definitive answer online. Thanks for any guidance offered.

Dear all I have 250g of Copper 250g of Tin and 250g of Sulfur. Everything is in powdered form. Heated up in closed container wit surrounding nitrogen flow to avoid contact with Oxygen. Heating ramp is 3 hours to 1000K. What reaction will be the leading reaction? How to calculate how fast will...

I have been contemplating for a few days now about how one could think about the electronic structure of Liquid metals. The cases of an isolated atom or that of solid metal crystal are well known and easy to understand. Though, a google search reveals (to me) that nothing much has come out for...

Hello, I am a high school student carrying out a physics experiment. I created a short circuit in order to see how much heat different types of metals would release when a current is running through them (4.5 A). In my experiment, I tested three different types of metals: Brass, Stainless...

(Heads-up: these might be QM questions) Two questions: 1.) What is it that gives rise to the fact that conductive metals provide a much lower potential for electrons to exist, than in free space? 2.) If conduction in wires take place due to an E-field that "travels" through/along...

And does rubidium ignite spontaneity in air...in powder phase or small piece of metal.

Homework Statement the answer is c) but i can't figure why ! is the more heat capacity substance lose and gain energy faster than the other one so it take more energy to get it's temperature raised by the same amount because it lose most of it very fast during the heating process ?

Is there a direct reason that gold, silver, and palladium are so much softer than the rest of the transition metals? Gold and silver are especially soft. I could not think of any reason myself, or in a quick search of the internet. Everything that I've come up with I've shot down. Thanks in...

Hey guys I've got an assignment. I need a comparison between a normal conductor and a semiconductor and why a classical understanding isn't enough to explain how an SC works. Also are there any electrical properties of an SC besides decreasing resisitivity at higher temps?

Hi, I'm really confused with how electrons become 'free' in a metal. I have a few questions and would be very grateful if someone could shed some light on them. 1. Are the electrons actually free? In a sense that the atom it is attached would essentially become an ion 2. If you take a copper...

Why is there such a large difference between the elastic moduli of metals and polymers? Is it because of different bonding? Or something do with the structure? Thank you!

In a solution of aqua regia (or other acids), if there is a precious metal dissolved, along with other metal ( such as other precious metals or base metals), and you add a powdered metal, you precipitate all the metals lower than it on the reactivity list. If however, you use a chemical...

Without moving macroscopic parts... No van de Graaff generators or piezo-something - just normal circuit that would used a battery at one point and on the other there would be macroscopicly charged electrode. :-)

I've learned that a more active metal displaces a less reactive one. So, according to the reactivity series Ca cannot displace Na but in he reaction given at http://en.wikipedia.org/wiki/Soap_scum Na is displaced by Ca. What is the reason for this exception?

what is the flame temperature for burning alkali metals in oxygen

Homework Statement A copper sheet of thickness 2.37mm is bonded to a Aluminum sheet of thickness 1.29mm. The outside surface of the copper sheet is held at a temperature of 100.0°C and the Aluminum sheet at 24.5°C. a) Determine the temperature of the copper-aluminum interface. b) How much...

Hello everyone! I'm a little confused. The Fermi-Dirac distribution is about every electron in a metal or only about the valence electrons?

Electric field of an electromagnetic wave incident on a metal accelerates free electrons, and these accelerating electrons then emit radiation opposite to the electric field of the wave, thus reducing the resultant amplitude in the forward direction. Radiation emitted in the backward direction...

What makes Fe, Co and Ni ferromagnetic compared to all other metals (with exception of Gd, Dy and some exotic alloys according to Wikipedia)? If other ferromagnetic metals just have lower Curie temperatures then why is it so? Sub-question: In pure metals is there any correlation in magnetic...

1. I would like to test myself on how well I know my information about certain metals, some of them get me a bit puzzled. How would you rate the electrical conductivity of cast iron? Poor, good, excellent or best? Also the thermal conductivity of 304 stainless steel? Poor, good, excellent or...

I would like to test myself on how well I know my information about certain metals, some of them get me a bit puzzled. How would you rate the electrical conductivity of cast iron? Poor, good, excellent or best? Also the thermal conductivity of 304 stainless steel? Poor, good, excellent...

Hi Fellow Members, I am a bit confused about delocalization concept. Since, in organic chemistry we have been told that delocalization only exits between conjugated systems but in inorganic chemistry there is delocalization of electrons in metals with no double bonds. Isn't it...

So I've tried to research a bit on refining aluminum without fluorine, and I came up with the idea of reacting the hydroxide off aluminum hydroxide with sodium or potassium. Only problem is, the reaction doesn't work, according to what I've found. I'm curious why, as the electronegativity...

metals are generally considered more useful for high strength parts because ceramics break when exposed to sudden shock, but what about when a continuous force is applied to a ceramic and a metal of the same dimensions by a high strength ceramic i mean a higher hardness than the metal (such as...

Does this construction even make sense? By definition it is a surface of constant energy in k-space, so for the free electron it is a sphere. But for metals you have band structure so that a given k-vector can have several different energies associated with it. Which of these are to be chosen?

Because of the "sea of electrons" holding a metal lattice together is it possible to charge that metal so much positively (by removing enough electrons) that it will break apart due to the unbalanced repulsion between positive nuclei? normally the interaction between the "sea of electrons" and...

Why can have transition metals unpaired electrons in their compounds? In correlates to their multiple oxidation states, but I still don't know the explanation of it, that would make me satisfied - I suppose it's mathematical, as molecular orbitals are creating. Or is there any explanation?

1. Regarding: Transition metals of the Periodic Table 2. Here's my question: the D-Block transition metals will always lose e- (& never gain e-'s) to fully fill (or half-fill) their d-subshells, right? 3. Given what I learned about stable, fully-filled and half-filled subshells...

Judging from the electron configurations, it appears to me that all transition metals in their normal state have 2 valence electrons. If it isn't, what are the valences of the transition metals, why can they have many different valences, and what are the 1B-8B columns for? Number of...

Why Fe, Co and Ni are ferromagnetic? what aspects of their electronic structure favors ferromagnetism? How 3d or 4f metals can be ferromagnetic and what is their origin of ferromagnetism?

Hello everyone here! See i got my hands on this paper: Optical properties of metallic films for vertical-cavity optoelectronic devices by Rakic et al. A simple google search of the title will give you access to the paper. Now, i am writing the function in MATLAB to calculate the...

I did an experiment, prompted by another thread, and saw something you kids probably see all the time: I was trying to measure the resistance of seawater, and came up with ≈11Ω. End of experiment, or so I thought... But then I decided that my battery voltage was a bit low and decided...

So I've heard of certain technologies that allow for heating of a certain type of metal inside of the body using external radiation. From what I understand, certain metals can be targeted while avoiding other metals. How does this "selective heating" process work.

At the moderators discretion; I have recently revisited the concept of the goldschmidt process of refining metals and in my searches found the similar process dubbed "the Ames Process" to refine uranium tetrafluoride into pure uranium. Though the process is already successful, the thought...

Hello everyone, a number of books and web articles says that the minimum field required is ≈10^7V/cm for electrons field emission/tunneling from the surface of metals. But fowler-nordheim formula shows that there is still considerable amount of field emission current density (mA/cm2) even...

I have been trying to find information on the crystal structure or phase of solid elemental metals at temperatures close to absolute zero, but I can only find information on there ambient structures. Does anyone know of any sources that would have thermodynamic tables for solid metals at low...

Why are hydroxides of Earth alkaline metals so insoluble in water? They are polar compounds and have an OH group, so they should do hydrogen bounds with water, as well as permanent dipole interactions, which in my conception are strong forces. Even Mg(OH)2, witch do not have a big mass, has a...

Homework Statement Do magnets attract all metals, and is the speed of light in a water constant? Homework Equations None that I know of The Attempt at a Solution I would assume that magnets attract almost all metals because they have an electron sea in them and they would be...

Trying to understand what happens upon impact to the metal of a car that is stopped (Vehicle 1)when another car's driver's side rear (Vehicle 2) impacts the stationary car . Vehicle 2 is a heavier, larger car and is moving in reverse at approximately 10-15 MPH. The impact site on Vehicle 1 is...

Hello, Is there a well known theory on how metals and semiconductors should behave, electrically, while under a high voltage bias? Say, 2-3V? For example, how does the conductivity change as a function of voltage bias as we go from the low bias regime into high bias? Is there a linear...

My syllabus notes the following points about transition metals and complex ions, but provides no textbook. d – and f – Block Elements Transition Elements General introduction, electronic configuration, occurrence and characteristics, general trends in properties of the first row...

What is the conductivity of metals at 0 kelvin? i think it will be zero because at 0 k entropy is zero. Every motion is cease.

Hi there, This could be absolute nonsense but I just got thinking about this. Say you had a certain metal into which a quantity of hydrogen had diffused, and then you placed it in communication with another hydrogen-free metal (say, titanium), would it be possible that the hydrogen would move...

Hi, someone was telling me that if you have two metals in close contact (like, one sputtered onto the other or something) with each other, if they have different work functions, you'll get some sort of diode effect (even without either of them being doped) if you have a current running from one...

I am studying for a test next tuesday, and I am having trouble on a couple of questions. The questions are... Question 1: Which of the following compounds would you expect to have to undergo electrolysis to obtain free metals? explain your choice. a. KCl b. Ag2O c. Fe2O3...