Is there any relationship between the number of valence electrons and how many?
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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.
120648
determine how many valence electrons each atom has. locate the central atom and spread out its valence electrons(each electron is represented by a dot). then pair up one from the atoms attached to the central atom. finally put all the other electrons for each outer atom around it.\nyou should see all electrons paired up, many times each atom will end up with eight electrons around it but many times there will be more or less than eight.
64224
All of the answers are in the periodic table. The atomic number is the number above the symbol. The number of protons is the atomic number. The number of electrons is the number of protons (if there's no charge). To find the number of valence electrons, look at the number of the column it's in (as in, Fluorine is in column #7, so it has 7 valence electrons).\n\nAs for the type of ion formed, everything to the left of the "staircase" (diving non-metals from metals) makes cations. Everything to the right makes anions.
937834
Well, you are getting in to a bit more complicated chemistry. For the question you are asking, the simple answer is No. However there are multi-valence ions, such as Oxygen. Normally Oxygen would gain 2 electrons making it O(2-) but it has another valence of 1 where it only gains one electron and becomes O(1-). By the sounds of it you are not at this point so don't worry about but you will get there eventually. In order to understand multi-valence you need a Periodic Table of Elements that lists all the valences of each element. This makes bonding harder, etc,etc so I wouldn't worry about it if I were you, yet.\n\nSo to simply answer your question, No, it is impossible for Magnesium
1026744
Valence, also known as valency or valency number, is a measure of the number of chemical bonds formed by the atoms of a given element. The concept was developed in the middle of the nineteenth century in an attempt to rationalize the formulae of different chemical compounds. Although it has fallen out of use in higher level work with the advances in the theory of chemical bonding, it is still widely used in elementary studies where it provides a heuristic introduction to the subject.\n\nIn chemistry, valence electrons are the electrons located within the outermost energy level of an atom. These electrons participate in chemical reactions. Elements with a full outer shell are very unreactive. Elements with an almost full or almost empty outer shell, such as the alkali metals and halogens, tend to be very reactive.
867500
O-1 will have 9 electrons and 7 valence electrons (1s2 2s2 2p5 : the outer (valence) shell has 2 from 2s and 5 from 2p)
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okay. i just took the test on this and passed with a B. so i promise i know what im doing.\n\nK, look at your elements. then look them up on the periodic table. lets pick, oh say the compout Cl(subscript)2O. that is 2 chlorines, and 1 oxygen. well, chlorine is in group 17, which means that each have 7 valence electrons, and oxygen is in group 16, which means that it has 6 valence electrons. following me so far? okay, take those valence electrons, and add them up. that equals 20 valence electrons. now, position the lewis dot diagram so that the oxygen is between the two chlorines. now, distribute the 20 electrons amongst the three letters, so that each has eight. now each letter should be surrounded by exactly eight dots. keep in mind that it should look like this -- :Cl:O:Cl:, but dots on the tops and bottoms. that is the lewis dot. luckily, this one did NOT have double or triple bondage. but in the event of double bondage, it might look like this -- :Cl::O:Cl, without dots all the way around each letter.\n\nand the VSEPR theoryis quite simple. it is just talking about the potential shapes that chemicals can make. for example, there is linear, or trigonal planar, or tetrahedral. this is vital. i promise that, if you contact me, i can give you a simple cheat sheet (not really for cheating, but it helps your memorization) to remember VSEPR. it gives you the shapes, lewis dot examples for the shapes, and angle measurements.\n\nhope this helps!\n~ally
1040753
The electron configuration is unusual because electrons prefer to be paired or alone in a subshell.  Since Chromium has 4 valence e-, one of the paired electrons of the 4s2 subshell moves into the 3d subshell, thus giving 5 unpaired e- in the 3d subshell, and one in the 4s subshell.  A similar concept applies to copper, just that in that case the e- from the 4s subshell makes 5 pairs of e- in the 3d subshell.
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The octet rule refers to Lewis dot diagrams and how electrons are arranged in molecules. During covalent bonding, atoms have eight electrons in their orbit, whether or not they are shared with another atom. An example of the octet rule would be oxygen atoms (each with 6 electrons) in a diatomic oxygen molecule sharing a total of four electrons between each other while keeping four electrons to themselves. Of course, the octet rule does not apply to hydrogen, which can only hold two electrons. The octet rule also applies to ionic bonding, where the anion (the negatively charged ion) gains a number of electrons to  have a total of eight electrons in its orbit.
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start with carbon... carbon has 4 electrons in it's valence shell.  carbon will almost always be the central element in your compound.  \n\nfor the first one... oxygen has 6 valence electrons... a triple bond joins the 2 elements (therefore they share 6 electrons) and each element has one pair of unshared electrons... it looks like this\n    :C:::O:\nnotice that each atom has 8 electrons... and you can count the ones that carbon donated and the ones oxygen donated... maybe this will make it clearer\n    :C:;;O;    imagine that each ; is a pair of electrons from oxygen\n\nok, the 2nd one is quite easy to explain, but difficult to draw on the computer...   Carbon is the central atom, with 4 electrons.  It shares one elctron with each of the 4 other elements.  Hydrogen has 1 electron, and needs just one more to complete its shell (it is unique in this way; most need 8, but hydrogen just needs 2).  Chlorine has 7 electrons in its outer shell and needs just one more to complete its outer shell.\n\nSo, the lewis structure is drawn in a cross fashion.  \n\nHorizontally...   H:C:Cl:::\n\nVertically...   H:C:Cl:::   (where they cross at the C)\n\nSo, C has a pair of electrons on each side, and each Cl has a pair of electrons on each side (not 3 pairs on one side as I have drawn)\n\nCheck out the attached link for more help
844206
The answer is simple. All elements (whose basic units are atoms) except the noble gases, have less than 8 electrons in their valence shells.  The rule that states that atoms should have 8 electrons to achieve stability is called The Octet Rule.\n\nhttp://en.wikipedia.org/wiki/Octet_rule\n\nThe way that they can attain 8 electrons is by forming BONDS: by either sharing electrons (covalent bond) or by gaining/losing electrons (ionic bond).   This is the main reason why atoms react: to attain 8 valence electrons.\n\nIf we look at it at another angle, we can say that atoms react in order to decrease energy.  This comes from the principle that bond formation results in loss of energy, and that stability comes from decreased energy.\n\nHope that helps.
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It is because a a shell can occupy only a maximum of 8 electrons which satisfies the octet rule.\n\n the rules are:\nHUND's rule of maximum multiplicity\nPAULI's exclusion principle\nAUFBAU principle
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None of the first two row elements can exceed 8 valance electrons.\n\nCarbon can make four covalent bonds. Oxygen (typically) only makes two covalent bonds since it already has two lone pairs. And hydrogen can only ever have one bond.
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a the number of outer electron that will bond with other atoms to fill thei valence shells
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The Lewis Dot diagram shows the number of electrons in the outer shell of an atom. These are also known as valence electrons. You simply determine the number of outer electrons an atom has, write the chemical symbol of the atom and by twos, place the same number of dots as there are outer electrons around the chemical symbol. Place the dots at the top, bottom, left, and right of the symbol.\n\nHow do you determine the number of outer electrons? Look at the periodic table. \n1. All the elements in the first column from Hydrogen to Francium all have 1 outer electron.\n2. All the elements in the second column from Beryllium to Radium have 2 outer electrons.\n3. Skip all the way to Boron. All the elements in that column have 3 outer electrons.\n4. Carbon's column has 4 outer electrons\n5. Nitrogen's column has 5. Oxygen's has 6. Fluorine's has 7\n6. Helium only has two, but the rest of the column under Helium has 8.
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Bond length = valence electrons divided by two.
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It does not just have to do with Bohr's quantum number (n). It is also to do with the angular momentum quantum number(L) and electron spin (+1/2 or -1/2). Therefore, if n=1, L can only = 0 and the result is 2 electons. One with a spin of +1/2 and the other with a spin of -1/2. \nIf n=3, L can be either 0,1, or 2. \nMeaning, \nif n=3 and L=0 this results in 2 electrons on the sub-shell. \nIf n=3 and L=1 this results in 6 electrons on the sub-shell. \nIf n=3 and L=2 this results in 10 electrons on the sub-shell.\n\nThis results in a maximum of 10+6+2 = 18 electrons in the shell.\n\nThis is because if L=2, the maximum number of possible electron states on a sub-shell of n=3 are as follows:\n\nGiven, m = -L, -(L-1)..0..(L-1), L\n\nm(magnetic quantum number) can have a value of -2, -1, 0, 1, 2 with the electrons having a spin of +1/2 or -1/2 resulting in a maximum of 10 electons in that sub-shell.\n\nThis is all based on the Pauli Exclusion Principle which states no two fermions (electrons) can exist on the same sub-shell with the same spin and magnetic quantum number(m).