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.
For a flat layout sheet metal part, is the bend line located directly in the middle of the bend allowance section, or is it inset from one side by a distance of the bend radius? So for a U-channel with an opening of approx. 4.56" (distance between inside of legs), would the distance between the...
Hello!
I'm having some trouble understanding stress and strain rations in sheet metal forming. I understand that they're constants, but how do you calculate them? Or are they usually given?
Thank you!
Hello! Can someone please tell me where I'm messing up in this problem?
At 4% and 8% elongation, the loads on a tensile test-piece of half-hard aluminium alloy are 1.59 kN and 1.66 kN respectively. The test-piece has an initial width of 10 mm, thickness of 1.4 mm and gauge length of 50 mm...
1. Homework Statement
Why is there no electric field strength in a metal sphere? Is it because the sum of the individial electric field strength of the charges in the sphere is zero? How is that possible?
Homework EquationsThe Attempt at a Solution
I know C=Epsilon0(A)/delta x
From the problem, C=3,000
Epsilon0 = 8.85 × 10^-12
and delta x is .5mm
The answer is supposed to be given in meters and should be close to 40,000 but I got 1.6*10^11m...help please!
I recently acquired a 39 gram sample of U-238 metal. I ran a gamma spectrum on the sample and found a major peak around 97 keV. I couldn't find any documents that mentioned this peak for U-238, but it is very prominent.
I ran a gamma ray spectrum on a 5 gram Uranium Oxide sample and it also...
I have approximately 30 pounds of discarded phone wire. I would like to recycle the metals (copper?) within, but don't know if it is feasible or even worth attempting. I also just returned from helping a parent clean out the garage, including a retired aerospace engineer's vast collection of...
Hi. I read that one method of hardening a metal is through strengthening with a second phase.
I'm not entirely sure I understand the phrase "strengthening with a second phase".
Can the phrase "strengthening with a second phase" be shown on a phase diagram? Thanks.
P.S. I seem to have...
https://www.yahoo.com/news/watch-metal-foam-dissolves-bullet-182400907.html
These materials look really interesting. I'd like to learn more about them, anybody familiar with these materials?
Homework Statement
An uncharged metal sphere hangs from a nylon thread. When a positively charged, nonconducting glass rod is brought close to the metal sphere, the sphere is drawn toward the rod. But if the sphere touches the rod, the sphere suddenly flies away from the rod. Explain why the...
Homework Statement
A metal sphere of charge +6μC is surrounded by a metal shell of net charge +6μC. Which of the following diagrams represents the electric field lines of the system?
Homework EquationsThe Attempt at a Solution
The correct answer provided by my teacher is a figure with 12...
Homework Statement
The specific heat capacity of a metal at low temperature (T) is given as ##C_p = 32\left({\dfrac{T}{400}}\right)^3## (kJK-1kg-1). A 100g vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work...
Dear Member,
Respected Members,
I am working on the behaviour of hydrogen at the Cu/Ni (111)-graphene interface. In case of Ni (111), the atomic H on the interface diffuse inside the the surface. While in case of Cu (111), the H atom stays at the Cu(111)-graphene interface. It seems that H...
I'm trying to understand the effect on a metal alloy of UV light (diode or laser) pulsing at about 1MHz.
I am assuming that the stirring of atoms will generate heat, possibly moving the alloy to its eutectic point (depending on the alloy) and in particular to atomic motion.
Can anyone...
Hi,
Is measuring the temperature dependent conductivity a reliable way of determining the activation energy/ the dopant level of a wide band-gap transition metal oxide. Also does the activation energy in this case change with the dopants density.
Thanks.
I've been using the following equation for thermal resistance to make basic calculations for a few different engineering designs: $$R_t = \frac{L}{kA} $$
Where L is the resistance path length, A is the cross-sectional area perpendicular to this path and k is the thermal conductivity of the...
Hello All
I could get some help I would greatly appreciate it.
I am trying to figure how to calculate the dissolution time of sphere undergoing constant corrosion at a rate
of corrosion.
Through a little google-fu, I found an article which gives me the solution (...
Hi. If a metal is very pure but still has other elements in it like this:
-1 or 2 at 500ppm, 1 at 150ppm, 2 or 3 at 20-30ppm, 1 or 2 at 3-5ppm. Which are manufacturing impurities and which are deliberate doping? Are the 500ppm doping?
Homework Statement
Uncharged metal plate area S and thickness d located at a distance r from the point charge q and oriented perpendicular to the vector r, as shown below. Find the electric force between the plate and the charge.
The plate thickness is less, and the distance r is much greater...
I am doing business with a Japanese partner to help japanese people to remain safe during earthquakes which require building a small metallic shelter in their homes, it should stand the destruction during an earthquake.
My question, what metal is the right choice? :oldconfused:
It must have...
Homework Statement
I had a lab where we put 50 grams of a metal smaple into a little bowl and then heated it with steam from a big beaker thing. Anyway, my question is about the errors I got in this lab when finding the specific heat of the metal. I had some high percent errors for Aluminum...
Homework Statement
This problem has two parts.
A laser produces photons having an energy, E = 3.5eV.
a) What is the wavelength of photons produced, assuming that the index of refraction is 1.6? ->221nm
b) If this laser beam is focused on the clean surface of a metal having a work function of...
I'll preface this with saying I'm an Industrial Designer, not an engineer. I also build workshop furniture as a hobby, which this question is in reference to.
I'm building a motorcycle lift table. I'm curious, is there a chart that compares things like tubing material, size, strength and...
Hi guys I was wondering of someone on here could briefly enlighten me on the chemical reactions that would occur with a Teflon Coated high carbon steel hook and a lead sinker while underwater? I am looking into the signals that may or may not be given off by these items both separately and with...
Hello.
I need to nickel plate an item, but there are no sources of pure nickel in my immediate area other than guitar strings. I picked up a set, which was labeled as pure nickel, but it was obvious upon inspection that only the wound strings had nickel, and that was only the woven outer layer...
how come they all cannot be reduced by a reducing agent such as hydrogen or carbon, why is it that only some can, the only thing i came up with is that, only those metals that are listed under the activity series can.
Homework Statement
At what rate does a 0.1m cube of metal with emissivity e=0.75 radiate energy if it is at a temperature of 200C?
Homework Equations
H=AeσT^4, σ=5.67 x10^-8
The Attempt at a Solution
I found the area of the cute to be A=(0.1m)^2=0.01m, and the turned 200C into 473K, but when...
Dear members,
Some days ago, I received the following exercise but I have never studied thermodynamics before and I don't know very well where to start, the exercise is about Heat Transfer and the Finite Difference Method and I must program the solution using Petsc and C++.
About the Finite...
I am trying to model metal NPs capped with organic agents to simulate their phase transfer behavior from aqueous to organic. Not doing computational chemistry courses has had me to disadvantage. Would love some initiation or a jump start primer for the same.
Looking forward for cues to get me...
A typical example is a iron chair gets cold in winters and wooden chain not. We all know iron is more conductive but how this thing possible at molecular level of conduction of heat from metal to air. In general conduction I know it is possible due to vibration transfer of molecules but how it's...
whenever any plate of system of parallel plates is earthed total charge on outer faces of the plates will become zero .Is it always true?or only in case of system of two plates?
I was just looking through a few different solutions in Griffiths EM and I must have not realized it, but do bound and free charges both contribute to the overall electric field?
For example: when dealing with a capacitor with a dielectric between it, one of the solutions wants to find the...
Can a large body of electrolyte be used for ground? For example, if we placed an insulated metal into the ocean. If it was charged, would the ocean water be treated as the other electrode in calculating it's capacitance?
I am thinking about using a metal mask for BOE or HF etching because I realize that for normal photoresist, it will gradually peel off and affect my results. I don't know which metal is the best--so far, I see people use Cr/Au, Al, and Ni. Anybody knows which metal will give the best result?
Hi all, first post here.
I'm currently faced with an assignment in a class where we really haven't been taught anything and have to figure it out on our own. We've been asked to design an industrial lift system to raise approximately 3000 kg up 25 stories. I have done a lot of research and...
If there is a small object with positive charge placed above a metal plate, the object induces a negative charge on the surface of the plate facing the object. Let's call this surface as S1.
(The metal plate is initially uncharged).
But from conservation of charge, the net charge in a metal...
Homework Statement
Problem 18B.13 from Transport Phenomena, BSL.
Tarnishing of metal surfaces. In the oxidation of most metals the volume of oxide produced is greater than that of the metal consumed. This oxide thus tends to form a compact film, effectively insulating the oxygen and metal from...
Homework Statement
Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as that of pure water at 20.0°C (18 torr). The volume of the mixture is 1.7 L, and its total pressure is 0.987 atm. Determine the number of moles...
Homework Statement
Two small bar magnets X and Y are released from rest at the same height above the ground. X falls directly to the ground, but Y passes through a metal right which is fixed with its plane horizontal. Does X reach the ground: (A) at the same time as Y, (B) before Y, (C) after...
Homework Statement
An otherwise free metal rod of length L = 67-cm is clamped at a point L/18 from one end. A standing wave is set up on the rod. What is its longest possible wavelength?
The Attempt at a Solution
where do I go wrong?
thanks
Hi All!
Haven't been here for some time, the changes are looking good!
Anyway, formalities aside, I am having serious problems sourcing and implementing a suitable stainless steel (Grade: 304; thickness: 0.3mm) substrate for my etching process.
I'm currently working on developing a...
Because China has flooded the market with cheap metal scrap dealers can no longer make money off of ferrous
metals, so what now, what can one do with the tones of metal scrap?
I almost "get" it, but not quite. Can someone help?
Here is my current understanding.
Say you solve the Kronig-Penny model. You find that you get bands of N closely spaced energy levels, with large gaps between them.
Under normal conditions, electrons fill the band to some level (let's say we...
We know that lithium, sodium and potassium tarnish when exposed to air, but rubidium and cesium catch on fire. Why is there such a huge jump in reactivity between Rb and K?
Homework Statement
the metal rod is supported by another metal rod at one end . The metal rod is supported by another metal rod at the end. so , the direction of tension of metal rod is acted upward , right ?( this is the initial prediction) But , i was told that the tension that we get from...
Homework Statement
earlier today i was doing some coursework to find the specific heat capacity of an unknown metal by submersing 100g / 0.1kg of the metal in boiling water above 75°C and record the temperature after 30 seconds (θm).
we then had to transfer the the metal from the boiling water...
Hi folks,
Just wondering if anyone can help with a few questions I have.
I'm working on a design of a gate which, instead of using a traditional hinge system, will consist of an outer cylindrical post with the gate leaf welded directly onto it, and an inner cylindrical post which will bear the...
Homework Statement
Find the potential outside a charged metal sphere (charge Q, radius R) placed in an otherwise uniform electric field E0. Explain clearly where you are setting the zero of potential.
2. The attempt at a solution
So for this problem I figured I could exploit superposition and...
i am wondering would that be possible to make a prince rupert's drop with metal..
would it end up having similar properties? (ie high compressive stress => stronger) or does molten metal flow too quickly?