What is Elements: Definition and 1000 Discussions

Éléments is a French bi-monthly magazine launched in September 1973 and associated with the Nouvelle Droite.
With a social and European inspiration, the magazine promotes a critical vision of liberal modernity on topics such as localism, ecology, respect for cultural diversity and the defence of European identity.

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  1. D

    Why actually are some elements radioactive?

    Can anyone explain to me why actually are some elements radioactive? I have the explanation in my textbook but i want to know the main reason why these elements are not stable...
  2. K

    How can we determine the number of elements in a set?

    I have the following problem: Suppose I have a set called "the white chess pieces on a chess board". I could say the set contains the following: king, queen, rook, bishop, knight, pawn. This means the set contains 6 elements. I could also say the set contains: king, queen, 2 rooks, 2 bishops...
  3. 3

    Conjugacy class with two elements in G implies that G is not simple

    Homework Statement If some conjugacy class of an element in a group G contains precisely two elements, show that G cannot be a simple group. The Attempt at a Solution This question was longer, with two questions before this one which I could answer and which probably lead to the answer on...
  4. P

    What elements are present in the sun and how do they form?

    I was reading something the other day on spectral readings from the sun, and I have a few questions regarding its composition. I know that there are heavier elements (gold, uranium, etc.) in the sun. I'm confused by this, as I didn't think there was enough energy to form such elements. My...
  5. M

    Question about the forming of heavy elements.

    I know that I'm told that the heaviest elements can only be created in massive supernovae. Is this just theory, or have we created, in labs, lighter elements in scaled down collisions/explosions?
  6. C

    Off-Diagonal Hamiltonian elements

    Hello, I just have a quick question about Quantum Mechanics. It's probably a bit basic but I'm trying to get my head around the off-diagonal Hamiltonian elements of a perturbation. We can assume the unperturbed Hamiltonian to be degenerate. If I have a Hamiltonian H=H_{0}+H' where the...
  7. S

    Fortran90 How to take the power of elements of an array to, say, 5?

    Hi all, as title, how to take the power of elements of an array to, say, 5? I know how to do it using loops, but would it be very troublesome if I have to do it a thousand times? Any ready made function in fortran90? I hope there is... I have googled it quite a bit, but seems nothing useful.
  8. K

    Grouping Elements: Making m Groups of n Elements w/ t Uses

    How many groups size m can you make from n elements (m<n) such that each element is used the same number of times t (t>0)? For instance, if you have 8 teams and group them in triplets, how many triplets do you need so that each team plays the same number of times?
  9. T

    Question about group 16 elements?

    Are group 16 elements more likely to form ionic or covalent compounds, and what is the most common type of ion they will form? Since they are nonmetals and have a negative charge, I am thinking they are more likely to produce ionic bonds and will form bonds most commonly with group 1...
  10. K

    Understanding Span: Multiple Elements in <x>

    If we call <a> the "span" of a, then I need some clarification on the concept of span. def. if G is a group and a∈G, then <a> denotes the set of all integral powers of a. Thus, <a> = {a^n : n∈ℤ} thm. Let S be any subset of a group G, and let <S> denote the intersection of all of the...
  11. A

    S_n acting on a set with more than n elements

    I'm wondering how the group S_n can act on a set with more than n elements? I'm basically only looking for some idea as to how to get started on describing such an action and how to think of that action. Thanks
  12. G

    For any two elements A and B that form AB, neither A nor B have to be

    For any two elements A and B that form AB, neither A nor B have to be invertible for (AB)-1 to exist, right?
  13. D

    Can Monoatomic Elements Really Have Superpowers?

    I didn't know where to start this so move it as needed, I have seen a bunch of "odd" info about monoatomic metals (mainly gold) and thought ya'll could answer some questions. exactly what is monoatomic? can gold, or any metal be made into a monoatomic element? is it indeed a...
  14. A

    Fortran Fortran 90 & elements array comparaison

    Dear all, I'm trying to figure about an efficient way to to get the redundant element in my array. For instance, let's take the array [0,2,3,0]. I'd like to get out [2,0,3] (or 3,0,2 it doesn't matter). So it find out which element is duplicated, an puts its value in between the 2 other...
  15. R

    Selection Sort on 1 Million Elements: Is It Feasible?

    if you have an array with size 1000000, would selection sort be feasible on a everyday laptop computer, or just too large? I imagine it would take (1Million)2/2 loops to complete the sort
  16. U

    Symmetry elements and reciprocal lattices.

    Hi, There are some points I really want to clear up in this topic...I promise to finish my chain of doubts as quicly as possible! I'll put in my first questions... 1. Rotoinversion is a combination of inversion and rotation-- often it ends up as having the same effect on the crystal as...
  17. H

    Finding the number of elements in a cyclic group

    How do we go about finding the number of elements of a cyclic subgroup that's generated by an element in the main group. For example: The subgroup Z30 generated by 25. I would think this subgroup would be {0,1,5,25} but there's supposed to be 6 elements and not four. Whats going on?
  18. A

    Does o(ab)=lcm(o(a),o(b)) for Group G Elements a & b?

    Suppose G is a group, a,b are two elements of G, does o(ab)=lcm(o(a),o(b))? o(ab) denotes the order of ab, lcm(o(a),o(b)) denotes the Least Common Multiple of o(a) & o(b).
  19. H

    Groups whose elements have order 2

    Homework Statement suppose that G is a group in which every non-identity element has order two. show that G is commutative. Homework Equations The Attempt at a Solution IS THIS CORRECT? ab=a[(ab)^2]b=(a^2)(ba)(b^2)=ba
  20. W

    Optical Spectra of Helium & Other Elements

    Homework Statement The following elements should have optical spectra similar to either a hydrogen atom or a helium atom. Indicate which of the following elements should have optical spectra similar to a helium atom. (Select all that apply.) The choices are: Cadmium, Lithium, Technetium...
  21. H

    Groups whose elements have order 2

    Homework Statement suppose that G is a group in which every non-identity element has order two. Show that G is commutative. Homework Equations The Attempt at a Solution Is my answer correct? Suppose that a,b and ab all have order two. we will show that a and b commute. By...
  22. H

    Groups whose elements have order 2

    Homework Statement Suppose that G is a group in which every non-identity element has order two. show that G is commutative. Homework Equations The Attempt at a Solution DOES THIS ANSWER THE QUESTION?: Notice first that x2 = 1 is equivalent to x = x−1. Since every element of G...
  23. K

    Minimum number of common elements in sets

    Hello, Let's say I have 500 boxes and 500 hundred non-identical items. I would like to have sets of 40, chosen among those 500 hundred items and my objective is to keep the number of same items in any 2 boxes at a minimum. 1. What would be that minimum number of common items? 2. If...
  24. J

    Finite Field Elements: F2n (1-8)

    Give one primitive element for each of the finite field: F2n (here "2" is the subscript) for n=1, n=2,...,n=8
  25. R

    Finite Elements in a Set of Rational Numbers Proof

    Homework Statement This problem is insanely intuitive. Define f : (0,1) \rightarrow \Re by f(x)=\begin{cases} 1/q&\text{if } x \neq 0 \text{, is rational, and }x = p/q \text{in lowest terms}\\ 0&\text{otherwise }\end{cases} Suppose \epsilon > 0. Prove that there are at most a...
  26. C

    Conjugacy classes of an elements in S_12

    I 'cheated' and used GAP to compute these, but I want to make sure I am thinking through these properly. This isn't homework as much as given answers in an example and I'm not sure how they computed them. S_12 (1,2)(3,4)(5,6)(7,8)(9,10)(11,12) - 10,395 This stems from...
  27. D

    Circuit Elements: Battery, Resistors & Capacitor Charge 195μs Post Switch Open

    Three resistors and a capacitor are in a circuit with a battery: R1 = 23 Ω R2 = 13 Ω R3 = 15 Ω C = 6.2 µF V = 17 V The switch has been closed for a long time. What will the charge be on the capacitor 195 μs after the switch is opened? picture...
  28. K

    Modal Analysis of Plate using lines and beam elements

    ANSYS Help: Simple Modal Analysis of Plate I am modeling a plate (36"x3"x.25") in ANSYS. When I construct a line out of two keypoints and give the line a rectangular section, the analysis works and I can output modal displacements just fine. With these modal displacements I can plot the mode...
  29. S

    Constructing a Set with One Element from Each Uncountably Infinite Subset

    Given a set of sets such that A_{i}\subset{C}. Every subset has a countable infinity of elements. I want to create a set W such that it contains exactly one element from each subset A_{i}. I presume I can do this by describing the intersect of W with every subset A_{i} as containing exactly one...
  30. S

    Shifting Vector Elements Left in MATLAB

    Homework Statement you are given a vector y construct a MATLAB script program to shift all element of y left by ( n ) position.. I mean if y=[1 5 6 9 3] and n=2 by apply this program on y we have : y=[3 1 5 6 9] The Attempt at a Solution this is my Attempt to solve this...
  31. J

    Engineering Circuit elements (Real or Imaginary)

    Statement: I was wondering if someone could provide more background knowledge on why certain elements in a circuit (e.g. capacitors) are associated with imaginary components, whereas other elements (e.g. resistors) are only associated with the real components. In particular, the equation below...
  32. D

    Question about origins of elements

    how is it known that iron is formed in stars and not anything heavier? And how is it known that elements like uranium arent in fact formed in the cores of stars prior to supernova? answers much appreciated
  33. G

    How did we get elements above lead?

    This is something which has been a question to me that I don't seem to have stumbled across anything about myself: How and when did/do the elements above Iron get created? I've come across mention about the elements up to iron being generated by the process of fusion in stars. I assume...
  34. R

    Debugging C Program for Outputting Array Elements

    C programme ? Homework Statement /* Program-8.4 */ #include <stdio.h> int main() { int marks[5]= {89, 45, 73, 98, 39}; printf("%d\n", marks); //memory addres pointed by pointer printf("%d\n", &marks[0]); //memory address of 1st element printf("%d\n", *marks)...
  35. H

    Derive flight path angle from orbital elements

    Hello everyone, During the last few days I've been working to solve a "small" problem I hope someone here might be better at than I am. I'm writing a function that returns the state vectors of an orbiting body of neglible mass based on the orbital elements semimajor axis, semiminor axis...
  36. wolram

    Primal plasma how many elements

    From the primal plasma how many elements (could) have formed that are not detected? or is the larder full.
  37. M

    Reflectivity of metals and elements

    Hello all, I was wondering if there was a way to calculate the reflectivity of differing wavelengths of light hitting an element based upon its physical properties. I know that it is based on how the atoms of the material are excited based upon the wavelength hitting it. I eventually want to...
  38. D

    Which elements of z42 are invertibles?

    Homework Statement which elements of z42 are invertibles? Homework Equations The Attempt at a Solution In my notes I have that invertibles are relatively prime to the order of the group. So I have 1, 5, 11, 13, 17, 19, 23, 25, 29, 31, 37, 41. Is that the case for all groups?
  39. L

    Aqueous and gaseous elements and compounds?

    Homework Statement Predict the sign of ΔS(sys) for each of the following processes: a) Zn(s)+2HCl(aq)-->H2(g)+ZnCl2(aq) b) CH3CH2CH3(g)+5O2(g)-->3CO2(g)+4H2O(l) Also, I'm not sure but when we're evaluating questions like these, do we count the number of moles only of solids, aqueous and...
  40. F

    Proving Even Cardinality of a Set w/o Inverse Elements in G

    Show that the Cardinality of a set which doesn't include inverse elements from a group G is always even. So the set with all g in G, which includes no inverse elements from G. (g=!g^-1) I can get this in every example I've done, checking mainly with dihedral groups, it's always been true but I...
  41. M

    Show every group of order 77 has elements of order 7 and 11

    Without Sylow's theorems! This was a problem at the end of a chapter on Lagrange's theorem. I know that every subgroup of order 77 is cyclic. But I don't know how to prove this using only Lagrange. Any suggestions?
  42. N

    Researching Elements - How Many Are There?

    Okay, so, in science class today, we learned about atoms and compounds and whatnot And I said to my teacher that I read somewhere that there are 131 elements, and she said that there are 90 main ones and about 17 others, and so she said that if I researched this some more, tell her. The book...
  43. S

    Can dark matter be trans-Seaborg elements?

    Hello everyone. May I ask if it's possible dark matter consists of trans-Seaborg elements beyond atomic number 126? Seaborg hypothesized that these elements were an "island of stability" and may be stable. Would we know enough of the chemical properties of such new elements to say that this...
  44. F

    Structure of elements of the unitary group

    Hey guys, I'm having a massive brain freeze here trying to show that for any element g in the unitary group you can always represent it as s*some diagonal matrix*s^-1. The only requirement for an element to be unitary is that its hermitian conjugate is its inverse correct? Any hints/help would...
  45. D

    Converting 2D Finite Element Code to 1D in MATLAB: Experience and Help Needed

    I need to convert a 2D code to 1D for a simply supported beam using matlab. Does anyone have any experience regarding to this?
  46. F

    How to find the distance between these elements?

    I'm studying the proof that the l2 metric space is complete and I just don't get something about this proof. What I know: l2 is the metric space whose elements are sequences that converge when you square each term and sum them. In other words, a sequence, f is in l2 if SUM( |f(k)|2) <...
  47. G

    Euclid's Elements at High School Level?

    Has anyone taught geometry at the high school level using Euclid's Elements (e.g., http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Euc.+toc") as a textbook? Einstein considered the Elements a "holy little geometry book."
  48. P

    Why is there variation in atomic weight of elements?

    I am trying to find a clear answer as to why elements' weights vary, when their makeup are of the same protons, electrons, and neutrons? For example, H = 1.0079 atomic weight, 1 proton + 1 electron Li = 6.941 atomic weight, 3 protons + 3 electrons + 4 neutrons If a neutron = 1 proton + 1...
  49. R

    A question of order of the product of two elements

    Let X = \{1,2,\cdots, p\} with p prime, and Y = \{1,2,\cdots,t,i_1,i_2,\cdots,i_{p - t}\} with 1\leq t\leq p - 1 and i_j\not\in X for 1\leq j\leq p - t. Supose that a and b are both p-rotation in X and Y, respectively. Whether or not p don't divide the order of ab?
  50. J

    My 3-Week Old Grand-Niece: Life's 4 Elements & 3 Forces

    I just went down to see my three-week old grand-niece. I have three grand-nephews on my side of the family and at least two on my wife's, she's not sure. This newly discovered particle has the following TOE: There are 4 elements, mommy, daddy, food, and sleep. Then there is the quintessential...
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