Periodic Definition and 437 Threads

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.

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  1. I

    What Determines When a Metal Ball Leaves an Oscillating Tray?

    Homework Statement A 1.50-kg, horizontal, uniform tray is attached to a vertical ideal spring of force constant 185 N/m and a 275-g metal ball is in the tray. The spring is below the tray, so it can oscillate up-and-down. The tray is then pushed down 15.0 cm below its equilibrium point (call...
  2. M

    Initial values lead to periodic solution

    Homework Statement Homework Equations How do you know when a given set of initial values for an ODE produce a periodic solution? The Attempt at a Solution I tried playing around with it for a bit and then searching the net but came up with nothing
  3. M

    Initial condition leads to periodic solution

    Hi, I have a question that asks me to explain how you could know if the initial conditions lead to a periodic solution of an ODE but I have no clue right now. I'd appreciate any help. Thanks edit: The question is a bit obscure because I am not sure if they are asking in general of for the...
  4. A

    Momentum eigenfunctions with periodic boundary conditions

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  5. H

    Solve Non-Periodic Signal Equation: (1-\nabla^2)B

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  6. tony873004

    Periodic motion, electric charge

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  7. M

    Periodic boundary conditions and Bloch's theorem

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  8. B

    Periodic Function: Derivative & Integral

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  9. Q

    Does any lattice or lattice shape has a periodic boundary condition?

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  10. P

    Calculating Density of SiO2 in the Periodic Table

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  11. D

    Fourier series periodic function

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  12. A

    Periodic table of the elements

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  13. C

    Are two signals that make up a periodic signal necessarily periodic?

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  14. T

    Periodic Table for solid state physicists

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  15. J

    What Function Models Yearly Sunrise Times in New York?

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  16. F

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  17. D

    How can a periodic function with period 1/2 be evaluated at specific values?

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  18. L

    Find b & r for Periodic Trajectory of f(x) = r*x/(1+x)^b

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  19. V

    Finding Exponential Fourier Series for a Periodic Signal

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  20. E

    Differential equation periodic and non periodic solutions.

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  21. V

    SHOW: x(at) is a periodic signal with period T/a (a>0)

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  22. J

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  23. T

    Periodic potential: Bloch's theorem

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  24. S

    Use the periodic table to write the electron configuration of Gd

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  25. G

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  26. J

    Is Memorizing the Periodic Table Necessary?

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  27. T

    Proving the Odd Function Property: f of f(x) as an Odd Function

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  28. MathematicalPhysicist

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  29. G01

    Laplace Transform of a periodic function

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  30. L

    Is This Periodic Function Even, Odd, or Neither?

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  31. A

    Is the First Digit of a Sequence of Numbers Always Periodic? (without prefix)

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  32. A

    Can You Create a Single Equation for Multiple Time-Dependent Cosine Functions?

    Given: x(t) = cos(2*pi*f1*t) 0 <= t < 4 cos(2*pi*f2*t) 4 <= t < 8 cos(2*pi*f3*t) 8 <= t < 12 f1, f2, and f3 are given as well Would it be possible to combine all three of these conditions into one convenient equation or am I just dreaming? I tried using Matlab to concatenate the three...
  33. L

    How Close is a Copper Bar to Breaking Under High Tensile Stress and Sound Waves?

    The tensile stress in a thick copper bar is 99.5% of its elastic breaking point of 13.0 X 10^10 N/m^2. A 500 Hz sound wave is transmitted through the material. (a) What displacement amplitude will cause the bar to break? (b) What is the maximum speed of the particle at this moment? Comments...
  34. M

    Periodic sound by a violin string

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  35. L

    No, I do not have a chart of trends in my text.

    Out of KF, NaF, and RbCl, does NaF have the shortest ionic bonds as well as highest lattice energy, and RbCl have the lowest melting point? Thanks
  36. N

    Solving Fourier Series for Periodic Functions

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  37. L

    Periodic Orbits: The Role of the Coulomb Potential in Producing Periodic Motion

    Let's consider the motion of a test particle in a central field. Is the Coulomb potential, 1/r, the only one that produces a periodic motion? If no, is there a condition for periodicity to occur? Thanks, Michel
  38. P

    Periodic Table Help: Group 18 Elements

    how many elements are there in group 18?
  39. kreil

    Intensity of periodic sound waves

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  40. K

    Periodic Table Programs & Posters: Download & Recommendations

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  41. W

    How can I prove that the product of two periodic functions also has a period P?

    I am trying to prove that if f(x) and g(x) both have period P, then f(x)*g(x) also has period P. What I tried to do was let f(x) and g(x) be represented as Fourier series f(x)=a_{0,1}+\sum_{n=1}^{\infty}\left[a_{n,1}cos(\frac{2{\pi}n}{P}x)+b_{n,1}sin(\frac{2{\pi}n}{P}x)\right]...
  42. G

    Understanding the Placement of Lanthanides and Actinides on the Periodic Table

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  43. K

    Creating periodic table w/ quantum numbers

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  44. L

    Number if rational iff it has periodic decimal expansion

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  45. L

    Prove the sum of 2 signals is periodic?

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  46. G

    How Much Should Rodolfo Paez Contribute Monthly for His Retirement?

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  47. C

    The Janet Periodic Table of Elements

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  48. A

    What is the Value of f(43) for a Function with a Period of 12?

    I can someone pleas help me with this problem? Thanks. A periodic function f has a period of 12. If f(7)=-2 and f(11)=9, determine the value of f (43) how do you do this?
  49. Nim

    Where to Find Element Properties at Standard Conditions?

    Im working on a periodic table in vb.net and I want to start adding in the information for the density, melting point and boiling point for the elements. The problem that I am having is I need to find a source that I know has only entered these values for a specific temp and pressure. I prefer...
  50. W

    Why Are Lanthanides and Actinides Separated on the Periodic Table?

    Why are there two rows separate from the general table at the bottom of the diagram? We just started chemistry this week and I'm interested in it, I might try to get it into an online course next year if at all possible, so I just felt like asking a question.
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