And In eaach square of periodic table, a what does the chemical symbol represent?what is the atomic mass denote? what does the atomic mass show?
205360
element in chemistry a substance that can not be decomposed  into similarsubstance by chemical mean.
380960
Here this is the link which is a bit useful it has element symbols on it .... but not their names, just put ur cursor on the elements it tells you the names\nhttp://acswebcontent.acs.org/periodic/tools/PT.html\n\nBut if u go to a bookstore or even a library im sure u'll find a much better one with informations. Just photocopy it. It's much better than lookin up on the net.
524452
If you have your periodic table handy, look at the key for the table, where it will tell you which corner of each element's block has the atomic radius.  You will notice that atomic radius tends to increase as you go down the rows of the table.  Makes sense; More electrons means a larger atom.  As you go from right to left, however, you will see that, in any one row, the radius decreases until you get to about the middle of the row; then the radius begins to increase with the atomic weight.  On any row, the element at the left end (lower atomic weight) has a larger diameter than the one on the right end (higher atomic weight).  All of this out of the way, Beryllium is larger than Carbon, which is in turn, larger than Nitrogen.
48807
Periodic Table is in order of increasing atomic no. so\n\n1st Step: find the placement of the element, in the present case it is on third place so no. of protons is three.\n\n2nd Step: In the Periodic Table, number of electron is always equal to number of protons so far three protons of Lithium there will be three electrons.\n\n3rd Step: Periodic Table also give atomic weights of the elements. Simply atomic weight is equal to sum of number of protons and nutroms.\n\n4th Step: Note the atomic weight of the element. Most of the elements in Periodic Table show atomic weights in fractions. In the case of Lithium it is 6.9 \n\n5th Step: Convert the fractional figure into nearest whole number. In case of Lithium it is 7\nNote:In the Periodic Table atomic weight is average of all isotopes (different atomic weights of same element). The nearest whole number refers to the most abundent  or the common atom (Isotop).\n\n6th Step: Subtract atomic number (protons) from atomic weight (neutron=proton), the difference is number of neutrons. In Lithium 7-3=4 so there are 4 neutrons
414388
1) Then all other varieties will have a relative mass of <1u. You should assign it to the variety with the smallest average mass.\n2) You are going to be a little more specific. E-mail me a scenario.\n3) The mass. Then you would get the atomic mass of the element from the Periodic Table and divide that from the mass of the sample element in question.
181837
ATOM..basic building block\n \n[Gr.,=uncuttable (indivisible)], basic unit of matter; more properly, the smallest unit of a chemical element having the properties of that element.  That is the definition.  Continue to read further; it really gives great detail!!!!!\n\nStructure of the Atom\n\nThe atom consists of a central, positively charged core, the nucleus, and negatively charged particles called electrons that are found in orbits around the nucleus.\n\nThe Nucleus\n\nAlmost the entire mass of the atom is concentrated in the nucleus, which occupies only a tiny fraction of the atom's volume. The nucleus of an atom consists of neutrons and protons, the neutron being an uncharged particle and the proton a positively charged one. Their masses are almost equal. Atoms containing the same number of protons but different numbers of neutrons represent different forms, or isotopes, of the same element.\n\nThe Electrons\n\nSurrounding the nucleus of an atom are its electrons; for a neutral atom, the number of electrons is equal to the atomic number. The outermost electrons of an atom determine its chemical and electrical properties. An atom may combine chemically with another atom in various ways, either by giving up or receiving electrons, thus setting up an electrical attraction between the atoms (see ion), or by sharing one or more pairs of electrons (see chemical bond). Because metals have few outermost electrons and tend to give them up easily, they are good conductors of electricity or heat (see conduction).\n\nThe electrons are often described as revolving about the nucleus as the planets revolve about the sun. This picture, however, is misleading. The quantum theory has shown that all particles in motion also have certain wave properties. For a particle the size of an electron, these properties are of considerable importance. As a result the electrons in an atom cannot be pictured as localized in space, but rather should be viewed as smeared out over the entire orbit so that they form a cloud of charge. The electron clouds around the nucleus represent regions in which the electrons are most likely to be found. The shapes of these clouds can be very complex, in marked contrast to the simple elliptical orbits of planets. Surprisingly, the sizes of all atoms are comparable, in spite of the large differences in the number of electrons they contain.\n\nAtomic Weight and Number\n\nThe atomic number of an atom is simply the number of protons in its nucleus. The atomic weight of an atom is given in most cases by the mass number of the atom, equal to the total number of protons and neutrons combined. An atom may be conveniently symbolized by its chemical symbol with the atomic number and mass number written as subscript and superscript, respectively. For example, the symbol for uranium is U (atomic number 92); the isotopes of uranium with atomic weights 235 and 238 are indicated by 23592U and 23892U.\n\nDevelopment of Atomic Theory\n\nEarly Atomic Theory\n\nThe atomic theory, which holds that matter is composed of tiny, indivisible particles in constant motion, was proposed in the 5th cent. by the Greek philosophers Leucippus and Democritus and was adopted by the Roman Lucretius. However, Aristotle did not accept the theory, and it was ignored for many centuries. Interest in the atomic theory was revived during the 18th cent. following work on the nature and behavior of gases (see gas laws).\n\nFrom Dalton to the Periodic Table\n\nModern atomic theory begins with the work of John Dalton, published in 1808. He held that all the atoms of an element are of exactly the same size and weight (see atomic weight) and are in these two respects unlike the atoms of any other element. He stated that atoms of the elements unite chemically in simple numerical ratios to form compounds. The best evidence for his theory was the experimentally verified law of simple multiple proportions, which gives a relation between the weights of two elements th
542695
coefficients denote how many ions you have, while subscripts denote how many of that element is in the molecule.  here, it should be a subscript, because you have 2 Cl-1, not one molecule of Cl(2)-1.
354579
OK, but you need to look up atomic weights or calculate molar mass.\n\n   Grams = Moles x molar mass  OR  moles x atomic mass\n\n    Moles = Grams/(molar mass) OR Grams/(atomic mass)
173360
mass # =#protons + # neutrons\nand # protons = # electrons in an electronically neutral atom.\nso you can therefore find the # nuetrons\n#neutrons=mass#-# protons
158898
Your second statement is correct, i.e proton mass+electron mass = constant mass and energy.\nok, This is with reference with another question you asked about mass defect(and chose my answer as the best, thanks). The sum of individual masses is greater than the actual mass of the atom. I am sure of this because this is what explains the stability of an atom(less energy, more stable).\nI'll give you an example which I took from my chem book\n\nMe = 0.0005486 amu(atomic mass unit)\nMp = 1.007277 amu\nMn = 1.008665 amu\nMe,Mp,Mn are masses of electron, proton and neutron respectively and 1 amu = 1.6605 x 10^-27 Kg\n\nOne He atom contains two electrons, two protons and two neutrons.\nSumming up the values of the constituents you get 4.032981amu as the expected mass of the atom.\nHowever the actual mass of the atom is 4.002603amu\nDifference = 0.030378 amu\n\nThe formula to find the binding evergy(energy required to bring the constituents together) is: mass defect x 931.48MeV\n\nHere that would be 0.030378 x 931.48 = 28.296 MeV\ni.e that is the equivalent of the mass defect in energy.\nThe '931.48' part is calculated using Einstein's formula E=mc^2.
514740
Okay this is kind of confusing but here goes...  Atoms have energy levels right?  There are sublevels to each major energy level, these are your s, p, d levels.  These sublevels can hold certain amounts of electrons.  S can hold 2.  P can hold 6.  D can hold 10.  These sublevels make up larger energy levels.  In the first major energy level there is only an S sublevel, so overall the first major energy level can oly hold 2 electrons.  In the second energy level there is an S sublevel and a P sublevel for a total of 8 electrons.  This keeps going on and on but I'll stop here    for now to keep it as simple as possible.  \n             Each element has a certain number of electrons.  The number of electrons is the same as its atomic number.  The atomic number is the number in the upper lefthand corner of the element's box on the periodic table.  The numbers go in order accross the table.  He has an atomic number of two.  This means it has two electrons.  You have to figure out which sublevels these electrons fill up.  Because there are only two electrons it can only fill up the first S sublevel.  So it is written    He 1s _2.  The 1 stands for the first major energy level.  The s is the sublevel and the 2 is the number of electrons in the sublevel when He is the element.  For He none of the other energy levels are used.\n             Ne has an atomic number of 10.  It has 10 electrons.  It fills up the first sublevel s and then moves to the second major energy level.  Here it fill up the s sublevel and the p sublevel (P can hold 6 electrons)  It can then be written  Ne 1s_2_2s_2_2p_6    Remember the number in front of the s of the p stands for the major energy level.  The letter( s or p) stands for the sublevel, and the number after the letter stand for the number of electrons in that sublevel for the given element.  Put a 0 in after the level not filled up.  \n         Hope this helps!  It's kind of hard to explain but I tried to make it clear.
266045
Chemistry is Chemistry (derived from alchemy) is the science of matter and study of inner molecules and atoms. You study metal properties, its characteristics and behaviour. You study about Organic and InOrganic Materials. You will also learn about mixing chemicals - Reactants and Products. Don't worry now, it will soon become interesting.\n\nThe atomic mass of a chemical element is the mass of an atom at rest and Atomic number (Z) is the number of protons found in the nucleus of an atom.
448113
First of all, look on your periodic table.  Somewhere there should be a listing for atomic mass.  Usually it's either at the very bottom of the square for that element or in a separate table.  That is how much that atom weighs in amu, or atomic mass units.  A molecule weighs as much as all the atoms in it put together.\n\nA guy named Avogadro came up with a number called Avogadro's number (modest character, wasn't he?) or a mole.  A mole is 6.023 * 10^23.  There are exactly one mole of amus in a gram.  Atoms are commonly measured in moles in the lab as well, since the actual number of atoms is usually way too high to work with conveniently.\n\nSo to answer your question, the number of atoms in a sample is (6.023 * 10^23 * the number of grams)/the atomic mass.  The number of molecules is (6.023 * 10^23 * the number of grams)/the sum of the atomic masses of the component atoms (also called the molecular mass).  But most of the time, amounts are reported in moles, and the number of moles is simply the number of grams/the atomic or molecular mass.\n\nI hope that made sense to you.
585860
Do a poster with charts of molecules, their chemical formulas, the masses of the elements in the formulas and how to derive their moleculare mass.  Then do a flow chart with the coversions between molecular mass, moles, particles and volume at STP.
396718
Re:  For Helium, the "2" is called the atomic number and it means that Helium has 2, protons, 2 nuetrons and 2 electrons.\n\nFor Lawrencium (Lr) it should show 103 as its atomic number.  That means that Lr has 103 protons, 103 neutrons and 103 electrons.  \n\nThe 2, 8, 18, 32, 32, 8, 3 numbers are showing electrons per shell (different subject) but you'll see that if you added all the numbers 2+ 8+ 18+ 32+ 32+ 8+ 3 = 103.  103 is the total number of electrons Lr has.   \n\n____________________________________________\n\n\n\n\nFor a Normal Neutral Atom, the number of protons (p+), neutrons (n) and electrons (e-) are all the same. \n\nJust look up the atomic number from the periodic table to determine them.\n\nFor example:\n\nC: 6p, 6n, and 6e-.\nN: 7p, 7n, and 7e-.\nK: 19p, 19n, and 19e-.\n\nNow, Determine the number of p, n, and e- for Ca.\n\n\n\n\n\n\nIf you guessed, 20p, 20n, and 20e-, you are Correct!\n\n\nNote that, if you add the number of the atom's p and n you will get the Mass number (Z). \n\nThe periodic table shows Z of calcium as 40.078 because 20p + 20n = 40 (amu) \n\nAnother Example: Oxygen, having atomic number of 8, will have:\n8p, 8n, and 8e-. This means that Oxygen will have the mass number of 16 because; p + n = Mass number (Z).\n\n______________________________...\n\nFor Isotopes:\nIsotopes are atoms that have same number of protons but different number of neutrons.\n\nYou've already seen that normal Carbon has: 6p, 6n, and 6e-.\n\nThis normal carbon is called "Carbon-12". The "12" denotes its Mass number (Z). Which is p + n.\n\nThere are isotopes of Carbons and one of them are Carbon-13. Since you already know that Carbon must have 6p, Carbon-13 has 7n. 13 - 6 = 7. The number of the electrons are still the same as number of proton. \n\nIn another words, simply subtract the number of protons from mass number to determine the number of neutrons.\n\nNow, determine the number of p, n and e- of Fluorine-19:\n\n\n\n\n\nIf you guessed 9p, 10n, and 9e-, you are Correct!\n\n______________________________...\n\nFinally, there are ions. Ions means that an atom has either gained or lost electrons. Keep in mind that eletrons are NEGATIVE in nature (e-) and when an atom Gains e-, it becomes More negative.\n\nFor example: Fluoride ion, F- means that it has GAINED one electron compared to its neutral F state. Therefore;\n\nF has 9p, 9n, and 9e-, But F- has 9p, 9n, and TEN e-.\n\nO has 8p, 8n, and 8e-, But O2- has 8p, 8n and TEN e-, because O2- means that it has Gained 2 more electrons than its normal O state. \n\nNow, determine the p, n and e- for P3-.\n\n\n\n\n\nIf you guessed 15p, 15n, and 18e- you are Correct!\n\nFor atoms that have positive charges (cation), remember that they LOSE e- to become positive. So, Li+ has 3p, 3n and 2e-. \n______________________________...\n\nKeep in mind that you need to know how to combine all three of the ideas mentioned above. For example, you may be requested to determine the p, n and e- of Magnesium-25 ion. \nYou need to know that since Magnesium is in Group IIA, it will turn into 2+ ion. Therefore Magnesium-25 ion will have 12p, 13n, and 10e-. \n\nI hope this answers your question. Good luck!
45900
The position of the elements in the periodic table gives you clues about the valences of each element. Also, if you remember the formulae for familiar substances (like carbon dioxide, water, sulfur dioxide, hydrochloric acid, etc) that will also give you clues about possible or likely valences. \n\nThe final answer is:\n\nmemorize.
368579
I would think your teacher is asking you about the way elements are grouped in the periodic table. You'll notice, for example, that gases are grouped together.\n\n Do a google on "classification of elements" -- there is a lot of stuff out there, and I'm sure it's also in your science text.