Elements Definition and 984 Threads

Homework Statement The last 2 parts of the attached photo. (4 and 6 marks) Im really not sure how to go about them in a (clever) way that won't take 2 hours. Homework Equations Possibly the fact that the product of the raising/lowering operators, J-J+ = J2x + J2y Answers to previous...

First off I am nothing of a scientist or chemist. can you add a oxygen molecule to say marijuana without screwing it up? or if i add one of the inert gases to it? haha, I'm just thinking out loud what you scientists say?

Hi to everyone, I have a problem with sizing pipe threaded elements. I am looking for guide rules that with a simple external meassurement I'll be able to determine the element size such as safety valves,threaded pipes,pressure gages,caps etc. To clarify my question, hereby an example, when...

Homework Statement Let R = Q[x]/(x^2-4x+4). Show that R has infinitely many nilpotent elements. Homework Equations The Attempt at a Solution I see that x^2-4x+4 = (x-2)(x-2) and that a nilpotent means a^2 = 0. Other than that, I'm not sure where to start.

Many physicists claim that decoherence determines the emergence of the worlds in the Many World Interpretation (MWI). I have always found such a claim elusively proved and actually wrong. Recently I wrote a paper: http://arxiv.org/abs/1008.3708 addressing such a subject, and I sent it to...

Homework Statement Let G be a group, and a an element of G of order m. What is the order of a^k? The Attempt at a Solution Well, first of all, if (a^k)^p = e, for some p, we have kp = mq, for some q. Now, for some k, the order of a^k is the least such p. Hence, it would make to sense...

Homework Statement Consider the elements marked with letters from a to h. Give the answer using these letters Homework Equations a) Give all of them which do not form compounds? b) Give all of them which form cations with charge 2+? c) Give all of them which form a gaseous molecule...

Prove that any two elements of order 3 in GL(2,Z) are conjugates. A paper on "the group of units of the integral group ring ZS3" by Hughes and Pearson refers to this result and says that it has been picked up from "Representation Theory of finite groups and associated algebras" by Curtis and...

So, the rule for finding the matrix elements of an operator is: \langle b_i|O|b_j\rangle Where the "b's" are vector of the basis set. Does this rule work if the basis is not orthonormal? Because I was checking this with regular linear algebra (in R3) (finding matrix elements of linear...

can anyone give me a first-order sentence that says there exist exactly three elements. Please explain it to me. Thanks

Homework Statement For any integer n>2, show that there are at least two elements in U(n) that satisfy x^2 = 1. Homework Equations None The Attempt at a Solution If the definition of the group U(n) is "the set of all positive integers less than n and relatively prime to n" then the...

Hello! I'm new to the forum so please don't mind any mishaps. I am very interested in the unstable radioactive elemts. I read that the thing that makes elements radioactive is ther different amounts of neutrons. Does this mean that all the radioactiive elements are radioactive just because...

Homework Statement Let v(t) = V_{max}\cos(\omega t ) be applied to (a) a pure resistor, (b) a pure capacitor (with zero initial capacitor voltage) and (c) a pure inductor (with zero initial inductor voltage). Find the average power absorbed by each element.Homework Equations P_{avg}(\tau) =...

I have several Questions. 1. What are the elements commonly used in a battery and why are they used? 2. What purpose does each chemichal in abattery serve 3. How does a battery truly work? thanks for answering, all postr will be helpful, BT

Hi, As part of my final year project I have to heat air within an exclosed environment (i.e. a 1m x 1m x 1m insulated box) to test the effectiveness of using phase change materials to regulate ambient air temperature. To do this I need to slowly heat the air inside the box at a rate that...

How did Dimitri Mendeleev know that some of the elements were missing/not discovered? How did he know that the missing elements existed? Did he find some sort of pattern when he created the Periodic Table?

Are there any simple elements out there that expose quadratic behavior? I. e. current to voltage or frequency to voltage or anything. I have done some google digging for multiplying circuits and found out that they are all very complex. But a simple circuit can be made using square function...

Homework Statement Show that the elements 3 and 2+\sqrt{-5} in \textbf{Z}[\sqrt{-5}] have a greatest common divisor of 1, but the ideal I = (3, 2+\sqrt{-5}) is not the total. Conclude that I is not principle. Homework Equations The Attempt at a Solution I have got as far as...

Assuming that super-heavy atoms were stable (at least up to 118), what would be some interesting chemical properties of some of them?

Can react with other atoms of their element and form diatomic molecules, while others cannot?

Because let's say we have Hydrogen and Chlorine, they with both react very well with each other due to the reason that Hydrogen wants to get rid of its only Valence electron, to have an empty shell, and Cl needs only one more to have a full shell. Right?

Homework Statement State the definitions of greatest and least elements in terms of strict orderings. Homework Equations Let \leq be an ordering of A and < be a strict ordering on A, and let B \subseteq A. b \in B is the greatest element of B in the ordering \leq if, for every x \in...

Is there a way to see that if \|x-y\| is "small", then so is \|x^{-1}-y^{-1}\|? For example, if \|x-y\|<r, is there a function f such that \|x^{-1}-y^{-1}\|<f(r) Edit: Nevermind. What I needed is just the operator version of (1/2-2/3)=(3-2)/6...

Homework Statement Let S(n,r) denote the number of elements of A_n of rank r. Then S(n,r) satisfies the recursion S(n,r)=(n-r)S(n-1,r-1) + S(n-1,r) Verify this formula for n=4 and r=0,1,2,3,4, using the values S(3,0) = 1 S(3,1)=3 S(3,2)=1 Homework Equations The Attempt at a...

Homework Statement Remember, the set of groups (Gn, *), the group of multiplicatively-invertible elements of Z/n under multiplication. For p a prime, the elements of Gp are all elements of Z/p except 0; for n not a prime, the elements of Gn are all the elements of Z/n except 0 and those...

Finding voltage across elements in phasor diagram, URGENT! Hi there, first time posting here, just caught up on a question with no worked solutions and it's driving me crazy! I've attached the question below,and the answer to b is v(t)= 5cos(2t-112). I can do part a but am struggling on...

Sorry if this question is too elementary (no pun intended) for this forum. If stellar fusion of iron takes more energy than it produces, how are heaver elements formed? Cheers, JP

Is there a website where you can enter the Compound's chemical formula and it's will give us the names of elements? like if i will enter to the website this chemical formula CH4 and it will give me the name Methane. thanks.

Homework Statement Prove that any group with three elements is isomorphic to Z_{3} Homework Equations The Attempt at a Solution Let G be the group of three elements We have an isomorphism if given c:G--->Z_{3}, if c is one-to -one and onto and c(ab)=c(a)c(b) First, we check...

I am a bit unfamiliar on this subject, but I know it has to do with the movement of electrons. From what I know, each atom has its own electric charge, metals are good electric conductors because the atoms have good current, so the charges can move from atom to atom easier. My question is, what...

Homework Statement For a biology lab dealing with chemistry, we are supposed to make models (ball and stick) of molecules, and then we need to write the structural and molecular formulas. The models should represent single or double bonds based on the molecular composition. The problem is...

I want to prove the following proposition: Given any uncountable set of real numbers S, there exists a countable sub-collection of numbers in S, whose sum is infinite. Please point me in the right direction.

Hello, let's consider, for example, the Clifford algebra CL(2,0) and the following mapping f for an arbitrary multivector: a + b\mathbf{e_1}+c\mathbf{e_2}+d\mathbf{e_{12}} \longmapsto a\mathbf{e_{12}} + b\mathbf{e_1}+c\mathbf{e_2}+d For vector spaces R^n we can permute the coordinates of...

Homework Statement Consider two fermion states: |n_1 n_2\rangle = a_{n_1}^\dagger a_{n_2}^\dagger|0\rangle and |n_1 n_3\rangle = a_{n_1}^\dagger a_{n_3}^\dagger|0\rangle where a_n^\dagger denotes the fermion creation operator in the single-particle state u_n\left(\vec{r},s\right)...

Rings and Fields - Write down the nine elements of F9[i] Homework Statement In F9 = Z/3Z, there is no solution of the equation x^2 = −1, just as in R. So “invent” a solution, call it 'i'. Then 'i' is a new “number” which satisfies i^2 = −1. Consider the set F9[i] consisting of all...

Say I have a sequence a(n) = 100 + n^2 with n ranging through the positive integers. I want to find the largest number g(n) such that g(n) = gcd(a(n), a(n+1)). Let g be a number that divides both a(n) and a(n+1) g | 100 + n^2 and g | 100 + n^2 + 2n + 1 therefore g | 2n + 1. This means that g...

Homework Statement Prove that an abelian group with two elements of order 2 must have a subgroup of order 4 Homework Equations The Attempt at a Solution Let G be an abelian group ==> for every a,b that belong to G ab=ba. Let a,b have order 2 ==> a^2 =e and b^2 = e. Since a...

I basically have this diagram: http://www.tinyimg.org/images/595physic144.png The problem asks "which of the elements are in series and which of the elements are in parallel?" I WANT to say that they are ALL in parallel with each other and none are in series, but I've never seen anything...

Homework Statement [PLAIN]http://img541.imageshack.us/img541/9880/34132542.gif The Attempt at a Solution For part (a), I think since the order of an element g is the smallest integer n such that gn=e, we will have: 8n mod 65 = 1 => n=4 64n mod 65 = 1 => n=2 14n mod 65 =1 =>...

this is from Nick Lane's Oxygen book I didn't quite understand this paragraph regarding the sudden release of a large amount of oxygen from cyanobacteria following the ice ages i don't understand how it's better to bury it. surely reacting with organic matter would be better as it is...

is it possible to separate the 3 elements in cloth Carbon,oxygen and Hydrogen without wetting it? Gas? Sound waves? Making the elements heavier?

On the table of elements chart it's known that many of the elements are man made? or at least a few of them? Curious, do we know more sure that we have made all of the elements that we can possibly make? Is that all the combinations of elements that can possibly exist? Is the theory valid...

Hi all I cannot understand Why Does the f-block elements differ in their electronic configuration from aufbau principle... Please I want to understand this particular mystery.. thanx

I'm looking to start working through one of these books. I don't read latin, so clearly it would have to be translated. There are so many editions of these works that I am having a really difficult time deciding which to get. The amazon.com reviews for all of them are good. I hope this is...

Why we have (although very little) on Earth heavy elemnents such as uranium, lead, ... if they weren't created in Big Bang or stellar nucleosynthesis (these proceses don't produce elements heavier than iron and nickel). Any guesses?

Is this set a variation of Russell's paradox? M = \{x : x \notin M \} I understand this formulation a lot more than R = \{S : S \notin S\} because I don't understand how, for example, 1 is a member of itself. Is 1 a set? Are all numbers sets?

Doing some quantum mechanics, I just ran into the notion of a matrix whose elements have matrix values for the first time. Specifically, a 2x2 matrix whose elements are 4x4 matrices. This got me wondering how I can extend the question into the absurd. I can't think of any good reason that...

I've been working my way through an old scientific paper on inductance calculation, and there's a fundamental principle I'm having a problem with. Suppose there are two filamentary conductors of any arbitrary shape. Now consider an infinitesimal element dl1 somewhere on the first conductor...

Statement: The ancient Greek philosopher Plato theorized that the http://en.wikipedia.org/wiki/Classical_element#Classical_elements_in_Greece". I'm not a philosophy or science student, so please keep your reply plain and straightforward. Thanks. I can understand the literal meaning of the...

So I heard a little rumor that Beta decays in certain isotopes release an electron at "ultrarelativistic" speeds. I also heard a rumor that Z bosons can be created temporarily by a positron annihilating an electron when the two collide. [FONT="Fixedsys"]My question is, can one place two...