What is Periodic: Definition and 434 Discussions

The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and nonmetals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals.
The elements from atomic numbers 1 (hydrogen) to 118 (oganesson) have all been discovered or synthesized, completing seven full rows of the periodic table. The first 94 elements, hydrogen to plutonium, all occur naturally, though some are found only in trace amounts and a few were discovered in nature only after having first been synthesized. Elements 95 to 118 have only been synthesized in laboratories, nuclear reactors, or nuclear explosions. The synthesis of elements having higher atomic numbers is currently being pursued: these elements would begin an eighth row, and theoretical work has been done to suggest possible candidates for this extension. Numerous synthetic radioisotopes of naturally occurring elements have also been produced in laboratories.
The organization of the periodic table can be used to derive relationships between the various element properties, and also to predict chemical properties and behaviours of undiscovered or newly synthesized elements. Russian chemist Dmitri Mendeleev published the first recognizable periodic table in 1869, developed mainly to illustrate periodic trends of the then-known elements. He also predicted some properties of unidentified elements that were expected to fill gaps within the table. Most of his forecasts soon proved to be correct, culminating with the discovery of gallium and germanium in 1875 and 1886 respectively, which corroborated his predictions. Mendeleev's idea has been slowly expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour. The modern periodic table now provides a useful framework for analyzing chemical reactions, and continues to be widely used in chemistry, nuclear physics and other sciences. Some discussion remains ongoing regarding the placement and categorisation of specific elements, the future extension and limits of the table, and whether there is an optimal form of the table.

View More On Wikipedia.org
Recent contents Top users
  1. F

    I Question about fitting periodic data

    My experience with data fitting is poor so I am in real need for help. The potential in the following is periodic over [0,Pi] I need to find a fitting function that I can use to perform further mathematics. Fourier series does not work, but a 40-degree polynomial give the following fit...
  2. Geek007

    Decomposition of apriodic and periodic signals

    Hi there, why the decomposition of periodic Composite signal give discrete frequencies and decomposition of aperiodic signal give continuous(in decimal) frequencies. please kindly do explain the concept behind in as simple words possible. Thanks
  3. Y

    A Periodic Function Looks Like This Formula?

    My book says this: I don't understand how this works. I learned that the usual sunisoidal function looks like sin(wt+phi), where w is frequency, t is time, and phi is some offset. EQ 17.1 doesn't match the bolded formula above. How does this work?
  4. F

    Periodic Table Element Names: Latin vs. Germanic

    Hi. Why do some countries use different names for the elements instead of their original names as indicated by their symbol? Like Na(natriu) is called sodium, Au(aur) is gold, Fe(fier) is iron, Cu(cupru) is copper, Ag(argint) is silver, Pb(plumb) is lead. I'm from a Latin/francophone country and...
  5. Anithadhruvbud

    Comparing Reactivity: F, Cl, and Br in the Periodic Table

    Amoung three elements F,CL,Br which is more reactive? I guessed it to be bromine because it has three shells and hence when we go down the group on the basis of their shells bromine will easily lose electrons. But the book says it is fluorine since it can easily gain electrons.And how can that...
  6. Priyadarshini

    Periodic Table and oxidising agent

    Homework Statement (i) An element that has a molecule which contains exactly four atoms. (ii) An element that reacts with water to give a solution that can behave as an oxidising agent. Homework EquationsThe Attempt at a Solution (i) Shouldn't it be boron? Boron forms BF3 which has four...
  7. DrClaude

    7th period of the periodic table now complete

    http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html
  8. M

    Fourier series of periodic function

    Homework Statement Periodic function P=3 f(t) = 0 if 0<t<1 1 if 1<t<2 0 if 2<t<3 a) Draw the graph of the function in the interval of [-3,6] b) Calculate the Fourier series of f(x) by calculating the coefficient. Homework EquationsThe Attempt at a Solution a) in attached...
  9. Karan Punjabi

    Explaining the Proton-to-Electron Ratio in the Periodic Table

    Hey guys we say that when in periodic table we go from left to right atomic size decreases because of increase in nuclear charge in the same shell but my question is that the electron to proton ratio is 1:1 then how nuclear charge is increased. Some say nuclear charge is concentrated but my...
  10. E

    Power of first three harmonics of periodic signal

    We know that periodic function can be written in terms of complex Fourier coefficients: $$f(t)=Fn0+\sum_{n=-\infty,n\neq 0}^{n=\infty}F_ne^{jnw_0t}$$, where $$Fn=\frac{1}{T}\int_{\tau}^{\tau+T}f(t)e^{-jnw_0t}dt$$ and $$Fn0$$ is DC component. Power spectrum of signal is defined as...
  11. D

    Periodic motion -- Potential as a function of a non-linear Force(x)

    Homework Statement Please see the attached.I don't know how to do (ai). potential function is the potential energy defined by f = -dV/dx e is the total energy of the system where e = KE + PE = (dx/dt)^2 /2 + V Note:m=1 because the particle has a unit mass If you integrate f,you get V(the...
  12. H

    Are all damped oscillations periodic?

    I know the equation for damped oscillation where the damping force depends on velocity. In that case the damped oscillation has a fixed angular frequency and thus time period! I am wondering if there are any types of damped oscillation where the time period is not constant i.e. the motion is not...
  13. F

    Is a Bloch wave periodic in reciprocal space?

    A Bloch wave has the following form.. ## \Psi_{nk}(r)=e^{ik\cdot r}u_{nk}(r)## The ##u_{nk}## part is said to be periodic in real space. But what about reciprocal space? I've had a hard time finding a direct answer to this question, but I seem to remember reading somewhere that the entire...
  14. evinda

    MHB Solve Periodic Problem: Find Function $u \in C^2(\mathbb{R})$

    Hello! (Wave) Periodic problem We are looking for a periodic function $u \in C^2(\mathbb{R})$ with period $(b-a)$ $$-u''+qu=f \text{ where } q,f \text{ periodic functions with period } (b-a) \\ u(a)=u(b) \\ u(x)=u(x+(b-a))$$ $x_i=a+ih \\ h=\frac{b-a}{N+1}$ $\mathbb{R}_{\text{per}}^{N+1}=\{...
  15. **Mariam**

    Pendulum periodic motion; period parameter

    Homework Statement A pendulum with a mass of 0.1 kg was released. The string made an angle of 7 ° with the vertical. The bob of the pendulum returns to its lowest point every 0.1 seconds. What is the period, frequency? Homework Equations T= 1/f T=sec/cycles F= cycles/sec The Attempt at a...
  16. K

    Prove f(x) = sin(x^2) isn't periodic

    Prove f(x) = sin(x^2) isn't periodic. f is periodic if f(x + t) = f(x) for all x in f's domain. I know about 1 way of proving it by derivative and boundedness but is this another way? If f is periodic then sin(x^2) = sin((x + t)^2) Finding t: (I don't know the proper way of doing this, maybe...
  17. Mister T

    Proposed Rearrangement of Periodic Table

    I'm sorry for being so vague here, but perhaps my post will ring a bell for someone who can fill in the details. A few weeks ago in a waiting room I was reading about a proposed rearrangement of the Periodic Table based on measurements of the ionization potentials (I think I got that right) of...
  18. W

    Periodic Functions: Is Irrationality the Cause of Non-Periodicity?

    Hey. Assume you have a signal ##f## with period ##T_f## and a signal ##g## with period ##T_g##. Then the signal ##h= f+g## is periodic iff ##T_f/T_g \in \mathbb{Q}##. So if ##T_f/T_g## is an irrational number, the signal ##h## will not be periodic. Why is this actually the case?
  19. Einj

    Generic Soliton Solution Periodicity: Restrictions & Examples

    Hello everyone, I have a question regarding the possible periodicity of time in a generic metric. Suppose that for some reason I have a solution to Einstein's equations of the kind (in Euclidean time): $$ ds^2_E=+f(r)dt_E^2+\frac{dr^2}{g(r)}+r^2(dx^2+dy^2). $$ Am I always allowed to assign...
  20. A

    Fluid problem - periodic forcing over a finite region

    Hello, I am working on a solo project outside my domain of expertise (Physics PhD student). I am trying to analyze/replicate the wave phenomena shown in the following video: To summarize what I am doing: I need to analyze a simple (cylindrical) pool, say 17.5" wide, 4" deep Figure out how...
  21. D

    Sum of Related Periodic Functions

    I have been looking through the book Counterexamples: From Elementary Calculus to the Beginning of Calculus and became interested in the section on periodic functions. I thought of the following question: Suppose you have a periodic real valued function f(x) with a fundamental period T. Let c...
  22. D

    Sum of Two Periodic Orthogonal Functions

    Homework Statement This problem is not from a textbook, it is something I have been thinking about after watching some lectures on Fourier series, the Fourier transform, and the Laplace transform. Suppose you have a real valued periodic function f with fundamental period R and a real valued...
  23. Q

    Solving for the number of periods in this question

    Homework Statement I hope everyone is having a great day. The equation I am working with at the moment is: (1+ (.2/x))^(x) = 1.21. 1.21 represents the final value, whereas 1 is the present value. I am trying to solve for x, which represents the number of periods necessary for the entity to...
  24. N

    FEM: periodic boundary conditions (1D)

    I am trying to set up the mass matrix for a 1D system which I want to solve using finite elements. So the mass matrix is defined as M = \int{NN^T}dL, where N is the finite element linear basis functions. I use hat functions. Say I have 10 elements, corresponding to 11 nodes running from -5...
  25. S

    What exactly is periodic motion?

    1. According to physicsclassroom.com, periodic motion is defined as "a motion that is regular and repeating." But the example included does not factor in damping (it's assumed that there's no air resistance and the spring will keep vibrating for eternity.)...
  26. W

    Periodic Boundary Conditions proof

    Hi! When we model bloch-waves in a solid we assume that there exist some kind of periodic boundary conditions such that the wave function is periodic. In 1D, ##\psi(x)## repeats itself for every ##L##, ##\psi(x) = \psi(x+L)##, such as here: OK, fine, we get pretty wave solutions if we assume...
  27. nusaiba mustafa

    What Are the Periodic Trends and Properties of Atomic Elements?

    I need a link or questions on periodic trends or periodic properties like on atomic radius,ionic radius,ionization energy,electron affinity,electropositivity and electonegativity Thanks Nusaiba mustafa
  28. Greg Bernhardt

    Insights It's Elemental. The Periodic Table quiz - Comments

    Greg Bernhardt submitted a new PF Insights post It's Elemental! The Periodic Table Quiz Continue reading the Original PF Insights Post.
  29. Atlas3

    Can time be a periodic function in GRFE?

    I am learning more about the Einstein Filed Equations. I do not know how to evaluate them. Can someone tell me if time can be a periodic function in the equation for spacetime? i may not have that spacetime correctly stated. Can time periodically vary like a SIN function and still work in the...
  30. A

    Singular spectral analysis of periodic series with period L

    Let's have a time series with a period=L. Suppose we arbitrarily choose the window length of the trajectory matrix to be equal to L which is also equal to the period of a time series. Then the second column of the matrix will also start with the same entry as the first column, because all...
  31. R

    Is 5s2 5p4 in Group 17 and Period 6 on a Different Periodic Table?

    Homework Statement In the long form of periodic table, the valence shell electronic configuration of 5s2 5p4 corresponds to the element present in A. Group 16 and period 5 B. Group 17 and period 6 C. Group 17 and period 5 D. Group 16 and period 6 Homework Equations NA The Attempt at a...
  32. L

    Inelastic collision affecting periodic motion

    Homework Statement A block os mass m is attached to a horizontal spring, which is attached to a wall. The block is oscillating without friction with initiation amplitude A0 and maximum velocity v0. When the block is at its maximum amplitude (and therefore instantaneously at rest), is it struck...
  33. S

    Question about the periodic table arrangement

    Hi, I'm new here. I'm actually studying the periodic table and while collectting the data on excel i noticed something. I wouldn't see it with the usual display of a periodic table but when you put it all in a sheet, ligns after ligns it become obvious to me. Argon Ar (noble gaz) is followed...
  34. Jewish_Vulcan

    Which mass number is shown on the periodic table?

    There are many different mass numbers for a given element known as isotopes. Are elements on the periodic table isotopes of their element? Why not use the average of all the mass numbers for an element?
  35. B

    Heat equation, periodic heating of a surface

    Homework Statement The temperature variation at the surface is described by a Fourier series \theta(t)=\sum^\infty_{n=-\infty}\theta_n e^{2\pi i n t /T} find an expression for the complex Fourier series of the temperature at depth d below the surface Homework Equations Solution of the...
  36. arpon

    Energy conservation and periodic motion

    Homework Statement Four weightless rods of length ##l## each are connected by hinged joints and form a rhomb (Fig. 48). A hinge A is fixed, and a load is suspended to a hinge C. Hinges D and B are connected by a weightless spring of length ##1.5l## in the undeformed state. In equilibrium, the...
  37. I

    Mathematica Mathematica Ndsolve periodic boundary conditions

    Hello, Mathematica is very new to me. Please help. n=1,2,3...,10 and stepsize between n(2)-n(1)=0.1 It is periodic. I mean n(11)=n(1). i have a initial function which depends on n and i want to solve this equation by NDsolve like that u[n, t = 0] == 1/(2*n + 1) Do [ u[n, 0], {n, 0, 10...
  38. H

    Periodic trends and effective nuclear charge

    My book is trying to explain why atomic radii decreases as you move toward the right side of the periodic table because the effective nuclear charge increases. I understand why an increase in effective nuclear charge results in a smaller radius, but I don't know why the effective nuclear charge...
  39. J

    Electric field of periodic charge density.

    Homework Statement Find electrostatic field and potential created by a two-dimensional charge density: \rho \sin (kx) \cos (ky) \delta (z) at the distance d from the the plane z=0 where the charge is placed (taking into account that it is embedded in a three dimensional space). In your...
  40. D

    Meaning of total ground state energy in periodic DFT calculations

    Dear all, periodic DFT codes (e.g. VASP) effectively simulate an infinite crystal due to the periodic boundary conditions. However, the energy value that one obtaines at the end of a simulation if finite. Frankly, I'm quite confused right now. Is the energy to be understood 'per unit cell'...
  41. R

    Periodic Boundary Conditions and which Hamiltonian to use

    Homework Statement Example Question: an electron with mass m is confined in a thin wire, with periodic boundary conditions applied in the x direction and harmonic potentials in the y and z direction. Write an expression for the wave functions in the ground state. Write down all the energy eigen...
  42. E

    Convolution Dirac impulse and periodic signal

    Hi ☺️ i have to do a convolution with a periodic signal and a dirac impulse: x(t)=sen(πt)(u(t)−u(t−2)) h(t)=u(t−1)−u(t−3) The first is a periodic graph that intersect axis x in points 0 , 1 and 2 (ecc) The se ing is a rectangle ( Dirac impulse ) that intersect AxiS x in points 1 and 3. For...
  43. R

    What are the most reactive elements in the periodic table?

    What are the most reactive elements in the periodic table?
  44. bibo_dvd

    Periodic Complex exponential signal

    hello guys .. first of all , iam not sure that i should type this thread here . so excuse me for that in this problem i can understand the part until it's said that w=0 then x(t)=1, which is periodic for any value of T but i can't understand the part after that in the case of w is not equal...
  45. B

    Automotive Car Periodic Vibration/Modulation Captured with App - Some Questions

    Hi Folks, Prior to leaving my car in for the annual MOT (UK), there were no vibrations to be felt at any speed. However, to pass the MOT I was advised to replace the 2 front tyres as they were worn. Ever since then, there is a periodic vibration which I can distinctly feel at 85mph but it is...
  46. David Carroll

    Rope swinging with periodic radius changes

    If one simply swings a rope with an object tied to the end of it, the object describes a circle. But if one were to create a contraption that caused the radius of the rope to periodically decrease 4 times every revolution, one could cause the path of the object to describe a square. My...
  47. W

    Schrodinger in a weak periodic potential

    Hi, I have problems figuring out what both c-coefficients means. Can someone explain this in a conceptual way? Also, Vg and V-g are the coefficients of the Fourier series if you expand V, but what does it mean physically? Thanks in advance.
  48. jimmy neutron

    Numerically solutions with periodic boundary conditions

    Is anyone aware of how to numerically solve the (1D) SE with periodic boundary conditions?
  49. R

    Periodic Solution to Differential Equation

    For each epsilon greater than 0, show that the differential equation x'=x^2-1-cos(t)-epsilon has at least one periodic solution with 0 less than x(t) less than or equal to (2+epsilon)^1/2
  50. C

    Where should hydrogen be placed in the periodic table?

    Hi all, I was always of the belief that hydrogen did not belong to any group in the periodic table. After discussions, some say that a group 1 or 7 place might be more suitable. Any opinions would be welcomed hopefully from a physics point-of-view on this topic.Thanks in advance
Back
Top