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Topic: List of elements by atomic number

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In the News (Thu 25 Apr 19)

  The world's top Chemistry websites
An element is a material that consists of atoms with a given number of protons in the nucleus.
This number is known as the atomic number of the element.
Lists of the elements by name, by symbol, and by atomic number are also available.
www.websbiggest.com /dir-wiki.cfm/Chemistry   (1089 words)

 List of elements by atomic number: Encyclopedia of chemistry, analytics & pharmaceutics with 64,564 entries.
The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table.
[209], indicates the mass number of the longest-lived isotope of the element or characteristic isotopic composition.
Atomic weights of elements with atomic numbers from 1-109 taken from this source.
www.chemie.de /lexikon/e/List_of_elements_by_atomic_number   (243 words)

Element: A chemical substance that cannot be divided into simple substances by chemical means; atomic species with same number of protons.
Isotope: An atomic form of an element having a particular number of neutrons.
Nuclide: elemental matter made up of atoms with identical nuclei, therefore with the same atomic number and the same mass number (equal to the sum of the number of protons and neutrons).
www.world-nuclear.org /info/inf51.html   (2742 words)

  Education Resources » List of elements by atomic number
[209], indicates the mass number of the longest-lived isotope of the element or characteristic isotopic composition.
Atomic weights of elements with atomic numbers from 1-109 taken from this source.
Atomic weights of elements with atomic numbers 110-116 taken from this source.
www.thecatalyst.org /resource/2006/04/21/List-of-elements-by-atomic-number   (360 words)

  List of Elements of the Periodic Table - Sorted by Atomic Number
Atomic number: The number of protons in an atom.
Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus.
Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus.
www.science.co.il /PTelements.asp   (516 words)

 Atomic number Summary
Atomic number is defined as the number of protons in the nucleus of an atom.
It soon came to be understood that the atomic number of an atom is equal to the number of protons in the atom's nucleus.
The atomic number is closely related to the mass number (although they should not be confused) which is the number of protons and neutrons in the nucleus of an atom.
www.bookrags.com /Atomic_number   (1356 words)

 Introduction - The Elements
He arranged all known chemical elements in order of their atomic weights and found that similar physical and chemical properties recurred every 7 elements for the lighter elements and every 17 elements for the heavier ones.
When ever an element is referred tro by an integer, that means the atomic number, not the atomic weight.
The atomic number not only the order of the elements in the periodic table; it is also the number of protons in an element.
library.thinkquest.org /10676/ele_intro.html   (582 words)

 Atomic Structure
The atomic number of an element determines the number of protons in an atom of the element.
The atomic mass of an element determines the number of protons and neutrons in one atom of that element.
The atomic number is 11 and the atomic mass is 23 (rounded to the nearest whole number).
www.augusta.tec.ga.us /chemistry/atomic.htm   (1311 words)

 The Periodic Table
During the next 200 years, a vast body of knowledge concerning the properties of elements and their compounds was acquired by chemists (view a 1790 article on the elements).
In 1913, Henry Moseley (see a picture) published the results of his measurements of the wavelengths of the x-ray spectral lines of a number of elements which showed that the ordering of the wavelengths of the x-ray emissions of the elements coincided with the ordering of the elements by atomic number.
With the discovery of isotopes of the elements, it became apparent that atomic weight was not the significant player in the periodic law as Mendeleev, Meyers and others had proposed, but rather, the properties of the elements varied periodically with atomic number.
www.wou.edu /liberalartsscience/physical_science/ch412/perhist.htm   (1833 words)

 Chemical Elements - Succeed in Physical Science   (Site not responding. Last check: 2007-10-29)
A chemical element (usually just called an element) is a class of atoms with a specific number of protons in their nuclei (plural of nucleus in Latin).
The average atomic weight is approximately the number of protons and neutrons of the most common isotope of the element.
Since the number of electrons equals the number of protons in an electrically stable atom, the atomic number determines many of the chemical characteristics of the element.
www.school-for-champions.com /science/elements.htm   (941 words)

 Introductory Terms, Page 2
By international agreement, the upper case letter Z is used to represent the atomic numbers of all the elements.
Atomic weight is the decimal number most commonly associated with each element's symbol on the Periodic Chart.
The values for the atomic weights of the elements are calculated by summing the products of the different individual Isotope Masses multiplied by the decimal equivalent of their percent of abundance values.
www.bcpl.net /~kdrews/introterms/intro2.html   (823 words)

 Atomic Theory
All atoms of an element have the same number of protons or atomic number, but their number of neutrons can be different.
During alpha decay, the mass of the parent atom decreases by 4 and the atomic number decreases by 2.
The number of decay is not completely regular, but on average the number of decays for a particular isotope is consistent.
www.rcs.k12.va.us /chemistrynhs/advanced/01_adv_atomic/advanced_atomic.htm   (4994 words)

 Periodic table - Pharmpedia
Progressing through a group from lightest element to heaviest element, the outer-shell electrons (those most readily accessible for participation in chemical reactions) are all in the same type of orbital, with a similar shape, but with increasingly higher energy and average distance from the nucleus.
francium, the heaviest element of the group, the outer-shell electron is in the seventh-shell orbital, significantly further out on average from the nucleus than those electrons filling all the shells below it in energy.
John Alexander Reina Newlands, who in 1865 noticed that the elements of similar type recurred at intervals of eight, which he likened to the octaves of music, though his law of octaves was ridiculed by his contemporaries.
www.pharmpedia.com /Periodic_table   (1355 words)

 Atomic Mass and Weight | World of Earth Science
Atomic mass is sometimes erroneously confused with atomic weight—the obsolete term for relative atomic mass.
Periodic tables, for example usually list the atomic weights of individual elements based upon the natural distribution of isotopes of that element.
The debate as to which element was to be used as the standard for atomic weights extended into the twentieth century, with the most popular positions being hydrogen with a weight of 1 or oxygen with a weight of 16.
www.bookrags.com /research/atomic-mass-and-weight-woes-01   (954 words)

 XML Schema Part 2: Datatypes Second Edition
The ·lexical space· of a ·list· datatype is a set of literals whose internal structure is a space-separated sequence of literals of the ·atomic· datatype of the items in the ·list·.
[Definition:]   The ·atomic· or ·union· datatype that participates in the definition of a ·list· datatype is known as the itemType of that ·list· datatype.
A literal in the ·lexical space· representing a decimal number d maps to the normalized value in the ·value space· of float that is closest to d in the sense defined by [Clinger, WD (1990)]; if d is exactly halfway between two such values then the even value is chosen.
www.w3.org /TR/xmlschema-2   (9338 words)

 Chemistry: Atomic Theory
An atom is the smallest unit of an element that retains the properties of that element.
The number of protons is referred to as the atomic number.
All of the elements to the left of this jagged line on the periodic table are metals (with the exception of Hydrogen); all of the metals to the right are nonmetals.
www.bsu.edu /web/jcflowers1/rlo/chematomictheory.htm   (2078 words)

 Cosmic Evolution - Epoch 3 - Stellar Evolution
FIGURE 3.45 — The Periodic Table of the Elements is a compact way to classify the physical and chemical properties of all known kinds of atoms.
The total number of isotopes is close to 2000 and growing larger each year as nuclear researchers discover more rare and exotic isotopes of the known elements.
Because such "helium capture" reactions are so frequent, elements numbered 12, 16, 20, 24, and 28 stand out as abundant "peaks" in the Figure 3.46, chart of cosmic abundances.
www.tufts.edu /as/wright_center/cosmic_evolution/docs/text/text_stel_6.html   (5325 words)

 List of Elements in Atomic Number Order
The difference between the atomic weight of the element in such specimens and that given in the Table may exceed the stated uncertainty.
Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material [range quoted for 1995 table 6.94 and 6.99].
[209], indicates the mass number of the longest-lived isotope of the element.
www.cartage.org.lb /en/themes/Sciences/Chemistry/Generalchemistry/Elements/NobleGases/NumberOrder/NumberOrder.htm   (254 words)

 Atomic Line List: Instructions
If the first number is smaller than the second number, this implies that the first option has been chosen, and otherwise the second option.
With this command it is possible to impose a lower limit on the abundances of elements to be considered for possible identifications.
If two numbers are present, the first is for the lower level and the second for the upper level.
www.pa.uky.edu /~peter/atomic/instruction.html   (1676 words)

 Compounds and Reagents
Periodic Table of the Elements at Los Alamos National Laboratory - a clickable imagemap of the Periodic Table of the elements.
A use for each element is cited, as well as its atomic number, symbol, weight, and electron configuration.
A variety of other information may be reported including sources of the element, its history, forms it occurs in, uses, and cost.
biotech.icmb.utexas.edu /pages/science/reagent.html   (589 words)

 Physics Documents
A nice way to draw the periodic table of the elements, as a cylinder with bulges.
atom, atomic number, nucleus, proton number, molar mass, nuclide, isotope, neutron number, nucleon number, and baryon number.
A discussion of why atomic physics says that electrons hate each other and pair up only as a last resort (Hund's rule #1) whereas high-school chemistry deals almost exclusively with molecules that have all their valence electrons paired up.
www.av8n.com /physics   (1681 words)

 NIST Physical Reference Data - Atomic Spectroscopy Data
The wavelengths, intensities, and spectrum assignments are given in a table for each element, and the data for the approximately 12,000 lines of all elements are also collected into a finding list, sorted by wavelength.
The energy levels and transition probabilities (where available) are listed for a total of about 2,400 of the most persistent lines and we also give a separate table of energy level data for each spectrum.
The available data include mean ion charges, ion populations, atomic process rates and other parameters over a wide range of temperatures and densities for a number of elements from C to Au.
physics.nist.gov /PhysRefData/contents-atomic.html   (1039 words)

 Extensible Markup Language (XML) 1.0 (Fourth Edition)
The root element of any document is considered to have signaled no intentions as regards application space handling, unless it provides a value for this attribute or the attribute is declared with a default value.
The element structure of an XML document may, for validation purposes, be constrained using element type and attribute-list declarations.
The content of an element matches a content model if and only if it is possible to trace out a path through the content model, obeying the sequence, choice, and repetition operators and matching each element in the content against an element type in the content model.
www.w3.org /TR/REC-xml   (8624 words)

 VisNetic Mail Server - Features
Lists can be administered by users or administrators via VisNetic WebMail, the Jabber Instant Messaging Client, and addresses can be added via the Challenge-Response Mechanism - e.g., if a message originator verifies himself as a legitimate source he or she can automatically be added to the white list.
When an IMAP user accesses their folder list, they will see both their private and shared folders; mail directories may be shared, while limiting each user to the mail server associated with their individual logon credentials.
If the number of attempts in a session exceeds the number specified by the Admin, the IP address of the sender will be remembered for that period and no access from that IP address will be allowed within the period.
www.deerfield.com /products/visnetic-mailserver/features   (2812 words)

 The chemical elements of the periodic table sorted by atomic number
The elemenents of the periodic table sorted by atomic number
For chemistry students and teachers: The tabular chart on the right is arranged by Atomic number.
Please note that the elements do not show their natural relation towards each other as in the Periodic system.
www.lenntech.com /Periodic-chart-elements/atomic-number.htm   (170 words)

 Nuclear constants help page   (Site not responding. Last check: 2007-10-29)
Lists of all isotopes of a given element, including number of protons Z and number of neutrons N.
The mass number, isotope or element for which information is desired is entered in "forms" with the keyboard.
For more advanced explorations of nuclear physics, such as comparing the mass excess as a function of atomic number and producing a graph of the relation for a range of isotopes, you may wish to know that the same information that is accessed by this page is available as a Mathematica package.
faraday.physics.utoronto.ca /nuclear/help.html   (612 words)

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