When arranged in order of increasing atomic number, the elements exhibit periodicity for all properties except
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b: mass just increases - no periodicity to it.
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Energy level is much more significant to atomic size.
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protons is the atomic number\nvalence electrons corresponds to this:\nGroup 1 (I) (alkali metals) :1\nGroup 2 (II) (alkaline earth metals) :2\nGroups 3-12 (transition metals) :1 or 2\nGroup 13 (III) (boron group) :3\nGroup 14 (IV) (carbon group) :4\nGroup 15 (V) (nitrogen group) :5\nGroup 17 (VII) (halogens) :7\nGroup 18 (VIII or 0) (noble gases) :8\n\n\nEvery element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons. It goes down the periodic table like that. At this time, the maximum number of electron orbitals or electron shells for any element is seven.
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http://en.wikipedia.org/wiki/Atomic_orbital\nhttp://winter.group.shef.ac.uk/orbitron/AOs/1s/index.html\n\n1s2, \n2 s2  2p6\n3s2  3p6  3d10\n4s2 4p6 4d10 4f14\n\nthey dont fill in that order though\n4s2 is filled before 3d10   (look on periodic table)\n5s2 before 4d10 and so on
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yes. in order for an atom to be stable, it must have eight valence electrons. In other words, each atom wants to have eight valence electrons. On the periodic table, you can determine what element can form a bond with any other elements. There are some elements which are an exception to the eight valence rule.
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Elements consist of a single type of atom.  For example, pure iron has only iron atoms.  Compounds combine more than one type of atom, for example, iron and oxygen form a compound called iron oxide, also known as rust.  Elements and compounds are alike because they cannot be separated into different materials by mechanical means, like filtering, magnetic separation or picking with tweezers.  The are different in that element have only one kinds of atom, while compounds have two or more types of atoms.  Even when you have material which is all one type of atom, such as a hydrogen gas cloud, a distinction is made between "elemental hydrogen", which is extremely reactive, and H2, which might need an outside source of energy to cause it to react with another element.
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Not only sodium rather all elements of s and p orbitals with 1 or 2 valency do not exist as naturally found pure elements.\n\nThis is because of their very high reactivity with majority of substances present in the atmosphere, sea and earth crust.
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The Periodic Table of the Elements, as developed by Mendeleev.
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Recognize the patterns that occur in the table; it is not called "periodic" without reason. It is also helpful to associate each category with a familiar elemet, for example, silicon with metalloids, as it makes one familar with the properties of that group.
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ok. To tell which elements are more metallic then others, It depends on the left over valence electrons that are attracted to the positively charged cations in a metal. To tell which elements are more active then others it is towards the right of the periodic table. Noble gases are non-reactive. To tell which atoms are bigger then others remember going from top to bottom in a group, atomic size increases, going from left to right across a period, atomic size decreases.(there is a pattern to this). \nI think if there are more valence electrons, the stronger the metallic bond is.
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if the atomic number changes, it becomes a different element\n\neach atomic number corresponds to a different element on the periodic table\n\nif hydrogen gains a proton, its atomic number goes up by one and it becomes helium
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The order of elements in the periodic table is determined by their atomic number, or number of protons (positively charged particles. The nucleus of the element is made up of protons and neutrons (neutral subatomic particles), and nearly all of the mass of the element resides here. \n\nElectrons "circle" the nucleus to even out the charge of the atom. The electrons organize themselves in layers, with a certain number of electrons in each layer. These layers are also referred to as the valence of the electron. The first layer has 2 electrons, the second and third have 8, the fourth has 18... These layers are what give the atom its volume.\n\nSince density is mass/volume, there isn't a linear relationship for density in each successive element, but the trend is density increases from left to right and top to bottom.
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Nobody knows the answer to this exept for Mendeleev himself, and he isn't talking. The first periodic table had 64 elements, although 3 or 4 of those were still purely theoretical. Since there were more than 50 in the first periodic table, you can't really discuss the first 50 added very well. Several models of organization were proposed, but there were around 60 known elements before it was deemed necessary to organize them. Only Mendeleev's used periodicity, and it is the closest to our modern periodic table.\n\nThe only 2 elements in my periodic table are:\n\nWOMANIUM (XX)\nPhysical properties: Generally soft and round in form. Boils at nothing and may freeze any time. Very bitter if not used well.\nChemical properties: Very active and highly unstable. Possesses strong affinity with gold, silver, platinum, and precious stones. Violent when left alone. Turns slightly green when placed next to a better specimen.\nUsage: An extremely good catalyst for dispersion of wealth.\nCaution: Highly explosive in inexperienced hands!\n\nMANIUM (XY)\nPhysical properties: Solid at room temperature but gets bent out of shape easily. Difficult to find a pure sample. Due to rust, aging samples are unable to conduct electricity as easily as young samples.\nChemical properties: Attempts to bond with XX any chance it can get. Also tends to form strong bonds with itself. Becomes explosive when mixed with Childrium for prolonged period of time.\nUsage: Possibly good methane source.\nCaution: In the absence of XX, this element rapidly decomposes and begins to smell.
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The only way to accommodate additional pairs of electrons is for the central atom to use its empty outer d orbitals in addition to its occupied s and p orbitals. Therefore, expanded octets occur around a central nonmetal from Period 3 or higher, those in which d orbitals are available.\n\nS, Cl, F
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They are arraigned in order of atomic number, that is, the number of protons in the nucleus of each element's atoms.
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positive ions (a positively charged element in this case since you specified 'atoms')  To be compounds, different types of atoms must combine.
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It is a table of all the atomic elements and the different building blocks of our world.\nThe periodic table is a table in which the chemical elements are arranged in order of their atomic numbers. With this arrangement, elements with similar chemical properties and electronic structures are displayed as vertical columns of the table.