A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride.
In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals can become nonmetals. Sodium, for example, becomes a nonmetal at pressure of just under two million times atmospheric pressure.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—arsenic and antimony—are commonly instead recognised as metalloids due to their chemistry (predominantly non-metallic for arsenic, and balanced between metallicity and nonmetallicity for antimony). Around 95 of the 118 elements in the periodic table are metals (or are likely to be such). The number is inexact as the boundaries between metals, nonmetals, and metalloids fluctuate slightly due to a lack of universally accepted definitions of the categories involved.
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than helium, and not just traditional metals. In this sense the first four "metals" collecting in stellar cores through nucleosynthesis are carbon, nitrogen, oxygen, and neon, all of which are strictly non-metals in chemistry. A star fuses lighter atoms, mostly hydrogen and helium, into heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements.Metals, as chemical elements, comprise 25% of the Earth's crust and are present in many aspects of modern life. The strength and resilience of some metals has led to their frequent use in, for example, high-rise building and bridge construction, as well as most vehicles, many home appliances, tools, pipes, and railroad tracks. Precious metals were historically used as coinage, but in the modern era, coinage metals have extended to at least 23 of the chemical elements.The history of refined metals is thought to begin with the use of copper about 11,000 years ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first known appearance of bronze in the 5th millennium BCE. Subsequent developments include the production of early forms of steel; the discovery of sodium—the first light metal—in 1809; the rise of modern alloy steels; and, since the end of World War II, the development of more sophisticated alloys.
Its given in my book that Sulphuric acid displaces more volatile acid from Metal salts like NaCl.
That is, NaCl + H2SO4→ HCl + Na2SO4
What does valtility have to do with such reactions?
Or Should I just accept it as a fact?
When a muon ( with energy around 1 GeV ) pass through a metal, such as Iron, which is about 1 mm in the z direction, how many energy the muon will lose ? Is there any formula to use?
Hello, I am a last year mechanical engineer student in Marocco, and i have no idea to solve a problem with my final year project, since we have never studied a thing about Metal fabrication.
The question is " give one method the Cone Deck could be formed in mass production assuming that flat...
I guess the question is also when.
If you have some food or liquid to store. If you use a low quality cooler bag with 200mL to 300mL Ice pack at what point will a Vacuum seal with no Ice beat the cooler bag?
I guess at the 10 hour mark or 24 hour mark or at some very long period of time.
My project involves making a 5 ft*3 ft*4 ft (l*b*h) aluminium/stainless steel sheet metal box at the back of a slow moving pedal vehicle. There is no load on the sheet metal, except from small vibrations from road travel.
My question is: 1. What gauge of sheet metal thickness would be enough...
Let's assume for a minute that money was of no concern. If one has a 10 MPa external environment and needs to have vacuumed-out spheres (or 1 atmosphere, close enough to call vacuum) inside of that environment.
In particular, I was thinking of a sandwiched lattice of maraging steel, with it's...
Homework Statement
I have 1.5 kgs of silicon with temperature 40 degrees celsius. It is dropped into 3 kgs of water holding temperature 25 degrees celsius. The system is heat isolated from the environment and the final temperature of the system is 26.2 degrees celsius. I need to find the...
In gold leaf electroscope
from the following video I have a doubt
From time 2:11 to 2:14 flow of negative charge i.e flow of electron won't it cause current?
Hello,
How do I take into account the difference in stiffness when fabricating a part (for example, an L-bracket) from sheet metal or using an extrusion?
In particular, where I work, it is "common knowledge" that extrusions are stiffer. How do i factor this in the stress and strain...
I was reading about semiconductor transparent conducting oxides and I found this why p-type conductivity is limited in TCOs. But I could not understand its meaning please someone explain me how the holes are localized at valance band edge and how dominated by oxygen- 2p levels?
''Owing to the...
Homework Statement
Two conductive metal plates are bonded together. Upon bonding, an oxide layer forms between them. The oxide layer is negligible thus the overall resistance of the plates is small. However I am having trouble finding this overall resistance, i.e., trying to find Cp and Rp...
Homework Statement
What is the maximum mass of lead you could melt with 2000 J of heat, starting from 25 ∘C ? Lead melts at 328∘C , its specific heat is 128 J/(kg⋅K) , and its heat of fusion is 2.5×10^4 J/kg .
Homework Equations
Need to find both the mass in the heat of transformation (Q =...
It has been my understanding when working with natural wood beams/joists, that for example, two 2x12 members over a 12' span gain significant strength when they are fastened (nailed, glued or both) together rather than just lying side by side touching one another.
Is this phenomenon...
Obviously there are MANY differences, but I'm curious about one in particular.
In an article I read, the creator used NiMH batteries because of their high charge density, but also because they do not require a charge controller and voltage regulator in the circuitry. Why is this, and is there...
Let's say you have a small metal case that is 3 inches by 3 inches versus 2 inches by 2 inches. Inside at center is a heat generating source (let's say a small processor chip). How efficient is the transfer of heat from the processor to the air... and from air to metal between the 2 different...
So i have this simple situation where i have an electron beam with a certain kinetic energy, and i have a metal plate connected to the ground, and the electrons hit the plate, now i want to know the voltage of the current in the wire to the ground. Now i know both kinetic energy of the electrons...
I've put a small battery powered commercial radio inside a Quality Street tin. The tin is all metal with rolled joints and the lid is a tight fit. I'd be willing to bet that there are no holes greater than 0.1mm around the lid's closure.
Why does the radio work when receiving an AM station (1...
I need to be able to support a variable side load up to a maximum of about 250lbs at 10' high. I am planning on using a 14' 4x4 steel pole that will be anchored 4ft in the ground (with concrete).
Question I have will 4x4 square pole be good for this application, and would 1/4" thickness...
How can I calculate the maximum load a shelf made from sheet metal can take at a certain deflection limit? Have a number of different sizes and gauges and need to calculate without testing.
Any help is much appreciated.
The shelf is supported in the 4 corners similar to photo below...
When photons reflect from a mirror coated with, say, an aluminium film... the reflection is presumably down to their interactions with free electrons in the metal (and each electron is in an unknown state before and after).
Yet the interference does not go away if a mirror is inserted in one...
Electrons pile up inside a metal up to a maximum value in k-space (meaning the have velocity) and occupying all levels at 0K, solving the Schroedinger equation as running waves. So electrons moving => radiation being emitted. But electrons can't move to a lower energy state, so that would mean...
So, I'm new around here and I'm not entirely sure if this is in the right section, but today I noticed something which I found thought-provoking. Before I go into this, I should point out that I'm 16, so all of my physics knowledge above high-school level is entirely self-taught, so I still have...
Homework Statement
Homework Equations
I have some equations relating B to I but I don't really know if they are useful
The Attempt at a Solution
I actually don't even know where to begin on this, my notes are confusing and vague :(
These are questions I've made up to try and wrap my head around the topic, so the theory within the questions themselves might be flawed.
1. Homework Statement
There are a number of metal sheets that are similar in every way except they each have slightly different masses. The temperature of...
I've read a few news articles recently about a Japanese team who've created a Jahn-Teller metal by injecting a rubidium atom into a bucky ball. They all mention a possibility of using it to create superconductor at high temperature, but the details are never there. Is this just a possibility...
Homework Statement
Homework Equations
ΔL = α L0 ΔT
The Attempt at a Solution
I converted the 0.62 mm to meters, giving 0.00062 m
am I suppose to convert the degrees from Celsius to K? why is the coefficient for steel in K-1? What does that even mean?
anyway, I converted C to K and answer I...
We know that,the shape of electric field line in a cylinder under varying magnetic field is circle,and I wonder,what's the situation if it is a piece of metal with rectangular cross section? I think it might be something like superellipses.Can somebody tell me is it true or how to treat this...
Homework Statement
Four identical parallel metal plates with area $$S$$ and distance between each two $$d$$ are located in air. The external plates are connected by wire. What is the equivalent capacitance between A and B?
This is problem from Irodov.Homework Equations
$$q=UC$$[/B]The Attempt...
Hello everyone, thank you for helping me in the other post, this one is different but includes pressure and how to calculate how much of it is present when an object is being "indented" or dug into.
I come from a forum that discusses fictional characters a lot and we find it highly enjoyable to...
Homework Statement
How much work would be required to remove a metal sheet from between the plates of a capacitor, assuming
a) the battery remains connected so the voltage remains constant
b) the battery is disconnected so the charge remains constantHomework Equations
When a metal sheet with...
Hi All,
Lets assume, we have piece of cubic copper of side length 1 cm metal with neutral charge, so:
1) The free electrons in this piece of copper exist everywhere as waves? , each electron with its quantum state.
2) On applying an external electric field the wave-function collapse and they...
Is there any way (ex. MO theory, valence electrons, etc) to determine the coordination number of a metal ion with another ion? I know it is generally a multiple of the oxidation number of the metal ion. However, for something like Ni and NH3. how would I know that it's a coordination number of 6?
Homework Statement
When the supply of oxygen is limited, iron metal reacts with
oxygen to produce a mixture of FeO and Fe2O3. In a certain
experiment, 20.00 g iron metal was reacted with 11.20 g oxygen
gas. After the experiment, the iron was totally consumed,
and 3.24 g oxygen gas remained...
Homework Statement
[/B]
A simple model of a railgun is a metal bar which runs on two long parallel rails. The two rails are connected to a charged capacitor with capacitance C and a resistor with resistance R. After charging, the capacitor can discharge through the circuit. You may assume that...
When a metal (electrode) is in contact with water, an equilibrium forms:
Mg ⇔Mg2++e-
Adding more of the metal Mg should convert some of it into more electrons so that the ratio of Mg to Mg2+ remains the same (as the equilibrium requires).
Therefore twice the amount of metal in contact with water...
The atoms in a metal (ex. Cu) are arranged as a 3-D grating. But to our common sense ,smooth metal surfaces only reflect lights. Why can't we see diffraction from metal surfaces?
Hi Forum,
Couple of pheromone here:
Metal reflects EM waves (visible light and lower)
Antenna absorbs EM waves
electrical circuit reflects high frequency signals inside the circuit
electrical wire with the right length and right signal becomes an open-circuit/Antenna
I think my question is...
Hey
Given the simple electric circuit below, the connection between the negative end of the DC source and the load (R1) is a pipe where heavy oil flow with some H2S and CO2. The pipe is made of iron and copper alloy.
Without the DC current, H2S and CO2 will corrode the pipe. After introducing...
In stories regarding the "Roswell UFO crash", there are claims of alien metal foil that (depending on who you ask! :) ) you couldn't cut with a knife, couldn't tear it by hand, and which you could crumple up, and when released from your hand, it would unfold again to a nice, smooth sheet.
Now...
Homework Statement
Estimate the resistivity of an amorphous metal whose mean free path is of the order of an atomic spacing. Compare your answer to crystalline copper.Homework Equations
VF = h(bar) KF / m
VF = l / τ
ρ = m / n e2 τ
The Attempt at a Solution
I think my real issue with this...
If there is a parallel plate capacitor with plate area, A, plate separation, d, and a slab of copper of thickness, b, is inserted exactly halfway between the plates. How to find it's new capacitance, C', and new potential difference, V' ?
Answer: V' = E(d-b) and C' = εA / (d-b)
I...
Hello guys I am working on designing somethings and I am using metal tubing. I do not know what type of metal tubing I am going to use this all depends on the math after I work my problem out. I am not sure what formulas to look up or what strength test I need to look up.
For example if I have...
I want to make a unibody, durable version of the above that won't chaffe skin and survives/resists getting distorted even if you try to twist the metal hook loop. Basically I have the above device. I pulled an twisted on the hook and the hook ripped out. I'm looking to create perhaps a metal or...
Homework Statement
Two large, flat metal plates are separated by a distance that is very small compared to their height and width. The conductors are given equal but opposite uniform surface charge densities +σ and -σ. Ignore edge effects and use Gauss's law to show
a) the electric field...
I am trying to use a metal film resistor to limit the current inside a dilution fridge (to reduce noise power from it), but I couldn't confirm if the metal film resistor is going to survive (or it goes superconducting) at ~3 Kelvin, searching a bit on the web but still I couldn't find the...
Hello,
I wonder whether I can replace the Metal gears and other parts with Plastic material? If so, what kind of plastic material should I use? There is no heat and the force is also not that great but the speed is.
This is not for toy but industrial machinery, with gear diameter of about 10...
Hey guys. I am currently building a plan for a new metal sculpture of an alien reptile thing. The twist for me is that I want it's scales to be rotatable from being flat up to a 45 degree angle. The pivot needed would have to be fairly small ( scales are nearly inch wide) . I could not find...