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.
I was thinking of a substance I could use to describe particle arrangement in solid/liquid/gas phases to school kids, and after realising water would be bad to use (since the liquid is denser than solid), I thought of using metal elements since they can exist in all phases.
Basically the...
I'm in the process of designing an escape system that uses a metal rope. I'm hoping to use a stopper so that the cable is not pulled too far and came across the attached. Unfortunately i do not know the jargon to be able to research it (Possible Materials, strength, sizes, etc) and was hoping...
Homework Statement
The graph in fig shows the stopping potential as a function of the frequency of the incident light falling on the metal surface.
Find the photoelectric work function for this metal
Homework Equations
V_0 =\frac{hf}{e}-\frac{\phi}{e}
The Attempt at a Solution...
Can anyone explain to me why most articles describe chromium as an acceptor in TiO2? In TiO2, titanium has the charge state Ti4+ and oxygen has the charge state O2-. When Cr substitutes for Ti, it does so as Cr3+. Now, at first glance, Cr has atomic number 24 and Ti 22. Cr therefore has two...
Lagrange Multiplier----to find out the dimensions when metal used min.
Homework Statement
I have a rectangular tank with a capacity of 1.0m^3. The tank is closed and the cover is made of metal half as thick as the sides and base. Find the dimensions of the tank for the total amount of metal...
Hello everybody
I have designed two small metal pieces (approx 30x30 mm) currently in 3D design that I now want to prepare for production by casting/molding. They are both intended for mass production hence price is a big concern, even the very small designchanges that may lead to reduction of...
Hi everybody,
Please forgive my question which is probably very obvious, but why are acids based on H ion concentration? Why is HCl a strong acid whereas LiCl is a salt. Both H and Li form + ions in solution. Conversely, why are OH- bases? Why can't NaCl be a strong base?
I'm sure the...
1. Homework Statement
I am trying to determine the limitations to my experiment and thus how to improve them.
The experiment's objective is to determine the mass of a metal rod.
The rod is balanced every time another 1kg is added onto the end of the rod.
This means that the rod cannot...
Help with "Balancing a metal rod" experiment.
1. Homework Statement
I am trying to determine the limitations to my experiment and thus how to improve them.
The experiment's objective is to determine the mass of a metal rod.
The rod is balanced every time another 1kg is added onto the end...
Stretch piece of metal within its elastic limit and it cools down.
Does it cool down for the same reason that a gas cools down when expanded?
But if the piece of metal is repeatedly stretched and released (like with a spring), I am led to believe that it heats up, although I am not sure.
I know...
Dear all,
I am a newbie in electromagnetic wave. Can you educate me, what will happen when an electromagnetic wave is blocked by a piece of flat metal placed in front of it?
My intention is to build a thermal chuck using peltier for to measure femto amps from my device.
I am worried if...
I saw a House episode where a person had internal bleeding because they had metal inside their body and they went into an MRI machine.
I'm learning about NMR now and I want to try and understand it more.
An ideal gas obeys Maxwell Boltzman statistics. Gas atoms
have an average kinetic energy of 3kT/2 but the individual atoms
have energies that vary from this average (Chi square distributed).
A solid (metal) has an average kinetic energy of about 3kT.
Does anybody know what statistical...
Homework Statement
A hollow metal cylinder has inner radius a, outer radius b, length L, and conductivity sigma. The current I is radially outward from the inner surface to the outer surface.
Find an expression for the electric field strength inside the metal as a function of the radius r...
Homework Statement
A metal sphere of radius 10 cm carries a charge of +2μC uniformly distributed over its surface. What is the magnitude of the electric field due to this sphere at a point 5.0 cm outside the sphere's surface?
8.0 x 109 N/C
4.2 x 106 N/C
8.0 x 107 N/C
4.0 x 109 N/C
4.0 x...
When a light wave of the form E=E0eiω hits the surface of a metal, the refractive index if given(considering restoring force of metal atoms and damping equal to 0), by n2=1-p2/ω2 where
p=plasma frequency and
ω= frequency of the wave.
In the case where n2<0,
n is complex. and hence the light wave...
I'm not taking this course for credit...
Hi! Is this a good text after Halliday?
I'm trying problem 7.7-
a metal bar of mass m slides frictionlessly on 2 conducting rails...
perhaps the current is I=integral J dot da, generated by the moving metal bar, velocity v (results in changing reference...
All
I understand clearly that if a metal sphere is charged then the charges must reside on the surface because that is the only way there is no electric field within the metal. However if you imagine a neutral metal sphere, and let's say it is suddenly enclosed by a uniformly charged metal...
Homework Statement
A ring of aluminum has a hole in the middle. When the ring is heated:
a) the hole decreases in diameter
b) the aluminum expands outward and the hole remains the same size.
c) the area of the hole expands by the same percent as the area of the aluminum.
d) the area of...
I'm studying the dispersive properties of metals using Lorentz-Drude model, but I'm confused about the equation set-up.
What is LD model different from the classical dielectric function using for other dielectrics? Namely: ε(w) = ε’ + iε’' where the imaginary part is the attenuation.
In...
Homework Statement
A metal rod (1/sqrt(pi)) m long rotates about one of its ends in a plane perpendicular to magnetic induction of 5*10^-3 T. Calculate the number of revolutions made by the rod if EMF induced between the ends of the rod is 1.5 mV.
I have been thinking about this problem for...
What causes flame color? I know light color corresponds to photon energy which is related to electrons relaxing from a high to low energy state.
I'm not sure how to conceptualize this situation though.
My professor was heating a 0.8 wt% carbon steel rod, in austenite phase, with a blow...
In DC motor or even in AC motor, if we use wooden frame and shaft, would it be advantageous than using Metal frame and shaft? Assume that would can with stand any temperature.
Hi,
Lets say I have two metal circular plates of diameter about 10mm.
If I press them together with a force of about 1-10N at temperature of 4K and hold them like that for couple of hours, will it be possible to separate them apart again at 4K (same environment) using no force (less than 1N) or...
Homework Statement
Two very small metal coated foam spheres, each of mass 2.80x10^-6kg, are attached to nylon threads 45cm long and hung from a common point. When the spheres are given equal quantities of negative charge, each supporting thread makes an angle of 15 degrees with the vertical...
Homework Statement
Two metal plates are placed in parallel, 2mm apart. They are then connected to a fully charged 9V battery. Without discharging the plates, the battery is removed, after which the separation between them is increased to 1 cm. What is the new potential difference between the...
When a metal gets polarized it looks like this: http://postimage.org/image/bkdw8ttgn/
However, only the electron moves towards the positive ion. Why is this so? As both experience an equal force despite the different accelerations, shouldn't both the positive ion and negative electron come...
Homework Statement
A metal sphere of radius r0 = 0.29 m carries a charge Q = 0.90 µC. Equipotential surfaces are to be drawn for 100 V intervals outside the sphere. Determine the radius r of the following equipotentials from the surface.
a) first:___m
b) tenth:___m
c) 100th:_____m...
Hey everyone,
In the process of wrapping my mind around the properties of metals for a realistic rpg combat system I'm working on, I made the following chart. Let me know what you think, if it's right (arrows pointing the right direction, covering the region, labeled correctly, etc), and if...
Homework Statement
2)Both, a brass tube and the steel rod located inside the brass tube are solidly attached to common end plates A and B at either end.
The respective diameters are :
Do = 5.4 [cm]
Di = 3.0 [cm]
d= 2.8[cm]
Brass:
alpha=19x10^-6/degree celcius
E=210GPa
Steel...
I was reading lately about fast reactors, breeders, and desirable high-temp reactors; and it seemed most new reactor concepts being studied today are more difficult than existing reactors in at least one way.
Supercritical water reactors need to battle with ever more hot and high pressure...
Homework Statement
Two concentric metal shells of radius a and b respectively ( a < b) are separated by weakly conducting material of varying conductivity σ(r) = kr where k is a constant and r is the distance from the common center.
If the metal shells are maintained at a constant...
Homework Statement
One end of a metal rod is maintained at 100°C, and the other end is placed in a large
container with ice and water at 0°C. The rod has length 50 cm and a cross-sectional area
of 0.8 cm
2
. The heat conducted by the rod melts 4 g of ice in 5 minutes. Calculate the...
Homework Statement
I understand how metallic oxide dissolve in water to produce OH- ion due to high electronegativity of oxygen. But I am having trouble understanding how non-metallic oxide dissolve in water to form acid?
For Homework I have to explain the reaction of Sulfur trioxide in water...
I'm trying to think about what it is I should be considering before I start throwing up some maths.
I'm thinking to assume that the positively charged core is a point charge +e and the electron is uniformly distributed over a sphere of radius Rs.
The self energy of the electron...
Homework Statement
Describe the ”conduction band” in Na metal. Why it is half-filled and
non-magnetic?
The Attempt at a Solution
Na has electron configuration: [Ne]3s^1
the 3s band is highest in energy and is the conduction band for Na. since Na has 1 electron in the 3s band, and...
Hello,
I would like to ask something here. If I would like to combine metal and fiber, what method is the the best because we can't simply glue them together. what material can hold them together. And can we test the strength of them after they stick together using ANSYS software? It would be...
I came across this piece of news, about how researchers have found a way to repel electric charges away from a surface:
http://phys.org/news/2013-01-metal-surface-repel-electric.html
I was thinking that perhaps it could be useful for more than just particle accelerator experiments. Could...
I'm working on my analysis of roof truss assignment and got stuck on the computation of dead loads having no value for metal furring load. I only have the value for wood furring which is 0.12 kPa. I've been searching in the internet but still I'm not able to find it. Thanks in advance.
Hello guys,
I wonder and would like to know what kind of metal to made a motorcycle chassis such as Yamaha YZF-R1 and Yamaha Raptor 700R?
Is it solid or hollow?
Is it cast or extrude?
Thank you
MyMachine
Homework Statement
we are considering the surface plasmon mode at the interface between a dielectric and a plasma. Solve explicitly for the TM mode and identify the relationship
between dielectric and plasma permittivities that must be satisfied for the mode to exist.
Homework Equations...
I'm working on a project to be exhibited early next year and I'm seeking some advice on one particular element.
The project explores the kinesthetic properties of sound, and the ability to transform an aural experience into a kinesthetic one.
A custom music track will play in the room...
A metal box will block most EM waves. Is this because the oscillating E field
will be canceled when in contact with the conductor. And because the oscillating E field
is the source of the changing B field does this then kill the B field.
Homework Statement
By considering the E and B fields of an incident monochromatic plane wave on a metal surface, as well as the current density of mobile electrons, J and the resulting EM force F felt by them, show that there is a force on the metal due to the magnetic force on the mobile...
Homework Statement
A uniform metal disk (M = 8.21 kg, R = 1.88 m) is free to oscillate as a physical pendulum about an axis through the edge. Find T, the period for small oscillations.
Homework Equations
I = mr^{2}/4
T = 2\pi √(I/mgd)
The Attempt at a Solution
I combined the formula...
the electrical resistivity ρ of a metal is proportional to the probability that an electron is seattered by the vibrating atoms in the lattice an this probability is in turn proportional to the mean square amplitude of vibration of these atoms.How dose the electrical resistivity ρ of the metal...
Hi, I have read about electric charge and tried to understand one particular thing but still couldnt:
If we positively charge a big metal plate with very high voltage and approach to it a small solid neutral metal sphere, the smaller sphere obviously will get attracted, i.e. a force will...
First off, sorry if this is a simple question, I'm very bad at electromagnetism.
Homework Statement
A metal ring of radius R rotates with constant angular velocity ω about a diameter. Perpendicular to the rotation axis is a constant magnetic induction field \underline{B}. Find the EMF...