How many valence electrons does a single, neutral bromine atom have?
443303
It only has 7 valence electrons :)\n\nRival
791559
Let's see, this may be a bit difficult to explain, but since no one else has so far, I figured I'd give it a shot.\n\nI don't have a periodic table in front of me, so I'll do my best to explain.  There is a double bond between N and one of the O's because of something called "in-bonds."  You determine the number of "in-bonds," or bonds in between elements by subtracting the number of valence electrons that you have all together from the number that you need for everything to be stable.  In this case, forget about H for the time being, and you have N03.  Each element needs 8 electrons to fill its valence shell right?  Multiply 8 by 4, since there are 4 elements, and you get 32.  However, you only have 24 electrons to go 'round.  The difference is 8, there for you can have a total of 8 electrons, or 4 individual bonds in between the elements.  It doesn't matter which O gets to share the double bond with N, as they are all the same.\n\nThe double bond was used in HNO3 and not NF3 because I believe you had enough electrons to go around, therefore there were no "in-bonds."\n\nI hope this helps to clear up your questions.
87059
You should consult a chemistry textbook, if possible, or if not, look online for an answer; I'm sure there is information or a guide describing how to do it better than I can in a few short sentences. That said, the basic way to draw a molecule (often abbreviated mlcl) is to use each element's symbol(ie sodium=Na, carbon=C, etc) to denote an atom, and to draw a single, solid line for each bond between elements. This line/bond represents 2 electrons, aka one orbital. Most elements like to have 8 electrons in their valence (outermost) shells in order to be stable, but this doesn't always happen; there are many exceptions, hence my suggestion to look at a textbook or online text/guide.\n\nIt gets more complicated when you're dealing with things like organic chemistry or complexes or chelating agents where sharing of bonds/electrons is pretty common and there are more types of bonds. For a simple example, if you had a 6-carbon atom ring, each carbon has 6 electrons in its valence; it wants 8, so what happens, does it get frustrated with its misfortune and self destruct, destroy our little universe? Of course not... there are a total of (6)(6)=36 electrons, and we need (6)(8)=48. How is this possible? Clearly, 36 is not equal to 48. We can't create more. So what happens? As it turns out, carbon, along with most other elements, passed kindergarten with flying colors- they SHARE them, and since it's a symmetrical hexagon shape of identical atoms, they are shared equally. There are all kinds of crazy combos in which the electrons are shared unequally between atoms because of something called electronegativity, but our rules for drawing those lopsided things aren't very different. However, that's for another 'lesson;' don't worry about it for now.\n\nSo, in order to make the carbon happy, we have to share 12, or 6 pairs, of electrons. ([48 needed]-[36 that we have] = 12) \nSince this carbon ring has multiple resonance structures (atom config the same but electron pairs on different atoms), we draw six carbons in a hexagon, with one solid line bond between each, and a dotted circle in the middle- this accounts for all of its resonance structures and provides us with more info, in addition to only needing one drawing to display that info, than using single bond lines only.\n\nSo in conclusion, I've said way more than I really had to... from the level of generality of your question I assume that you don't know too much about chemistry; if you are confused with what I said, then do as I said- look up the info online or get a book. It's not too easy to understand right away but with some patience you should be able to figure it out just fine; good luck.
429543
Filling its valence shell with paired electrons.
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.
786820
Flourines electron configuration is [He]2s2 2p5.  In the p-orbitals there are three subshells, each subshell is capable of taking only two electrons a piece.  This leaves you with one electron that is unpaired.  Because in the p-orbitals you can only have a total of 6 electrons.  So, 6-5=1.
906889
Valence electrons are those electrons in an atom outside the noble-gas core.  Valance electrons are the electrons in the outermost principal quantum level.  Valance electrons are the electrons which are most often involved in reactions and forming chemical bonds.\n\nPotassium has a single valence electron, 4s1, which comes from the 4s subshell.\n\nChlorine has a total of seven valence electrons, 3s2 3p5, two from the 3s subshell and five from the 3p subshell.\n\nGold = 5d10 6s1\n\nNeodymium - 4f4 6s2\n\nYou can look up each element at the site below.
234889
...valence, the number of electrons it can donate or accept.\n\nhttp://www.mhhe.com/biosci/genbio/guttman/student/olc2/chap03outline.html
938770
That would be 9 total electrons and 7 valence electrons
908581
C, Al(OH)3...\nWould you like an explanation? Okay, I'm supposed to be learning about this in Chemistry right now, so, I think this is how it works...\n\nIf you study the periodic table of elements, then you will find the number of valence (or outer) electrons each element has. Al has 3, O has 6, and H has 1. Before we start, it is important to know that a filled orbital has 8 valence electrons... okay? \nO and H combine, so they have a total of 7 valence electrons. You can imagine this by thinking of the letters OH surrounded by 7 dots in a circle, 2 pairs of dots on each side and 1 alone (a filled orbital with have four pairs opposite each other). The lone pair needs an electron, so it can borrow one from aluminum, which has 3 electrons. Aluminum loses its electron, so now it has 2, and the OH is now full, because it has 8 electrons. However, the aluminum has to get rid of its other two electrons, so another OH is brought in. The aluminum gives up an electron and the second OH is now full. Finally, the last OH pair is brought in and the aluminum gives away its last electron. So now, it is empty and the OH's are full. I guess they're balanced. Anyway, you are now left with 1 Al and 3 OH's, making Al(OH)3. Do you understand now? \n\nAl (3), and OH (7) (because O=6 & H=1, which equals 7)...\nAl - 1 = (2), so now OH = (8) (now it's full)\nAl - 1 = (1), so a 2nd OH (7) is brought in, making it OH (8)\nAl - 1 = (0), so a 3rd OH (7) is brought in, making it OH (8)\n\nIt took 1 Al and 3 OH's, so the new compound is Al(OH)3\nHope this helps!!!\nP.S. sorry for any confusion earlier when I tried to "draw" them. The computer changed the spacing so all you could see was a mess of stars and stuff. : )
844224
You  have more than one question about isotopes - do a search for the isotopes and that should give you what you are looking for.  There are 26 bromine isotopes.
712831
The Relationship of Electrons and Valence\n\nFor purposes of describing chemical behavior, an atom can be considered as a positively charged nucleus surrounded by negatively charged electrons orbiting in concentric spherical shells. The number of positive charges in the nucleus determines how many electrons normally surround the nucleus; as atomic number increases, the electron shells are filled, starting with those nearest the nucleus.\n\nThe valence of an atom is determined by the number of electrons in the outermost, or valence, shell. The atom exists in its most stable configuration when its outermost shell is completely filled; in combining with other atoms, it thus tends to gain or lose valence electrons in order to attain a stable configuration. If the valence shell of the atom is nearly complete, as in chlorine and other nonmetals, the atom will tend to accept electrons to complete it; if the valence shell has few electrons, as in potassium and other metals, the atom will tend to lose these electrons, so that the next shell below the valence shell becomes a completed outermost shell.\n\nThe valence of many elements is determined from their ability to combine with hydrogen or to replace it in compounds. For example, one oxygen atom combines with two hydrogen atoms to form water and the valence of oxygen is thus determined to be 2. Similarly, chlorine accepts one electron in combining with a single atom of hydrogen to form hydrogen chloride, HCl, and chlorine's valence is 1. Zinc does not combine with hydrogen but does replace it in compounds; in a typical replacement reaction, one zinc atom replaces two hydrogen atoms, as in the equation Zn+H2SO4→ZnSO4+H2, so that zinc has a valence of 2.
402942
An atom is stable when it has a full valence (outer) electron shell.  For the first row on the periodic table, the outer (and only) shell can hold up to 2 electrons.  For the next two rows, the atoms' outer shells can hold up to 8 electrons.  The next two can hold up to 18.\n\nAtoms like sodium, in column 1 of the periodic table, have one electron in its valence shell.  It is very reactive, since it wants to get rid of this extra electron so that its outer shell can be full.\n\nAtoms like chlorine, in the second last column, have one electron missing from their valence shells.  They are also very reactive, since they want to accept an electron to fill the outer shell.\n\nNoble gases are almost totally unreactive, since they have the unique property of having full outer shells without having to give away or accept any electrons.
748503
s p d f blocks tell which set of orbitals are the last to fill for those elements.\n\n+ or - depending on whether it will lose or gain an e-\n\ncations are smaller than atoms b/c they lose e-\nanions are larger than atoms b/c they gain e-\n\neach successive ionization energy gets higher becasue the #protons is more and more unbalanced by # e-\n\nhalogens have 7 valence e- and noble gases have 8.  by gaining one e- the halogens now have the e- configuration of a noble gas and are more stable.  gain 1 e- = 1- charge
347007
The valency is determined by how many electrons the atom is using to bond with another atom to form a compound. The electrons in the outermost orbit generally forms the bonds. For materials having multiple electrons in the outermost orbit the element can have different valencies. Whatever happens tends to lower the the total energy of the system to make it stable.
62273
Arsenic has exactly 3 electrons in its 4p orbitals, meaning exactly one electron in each orbital.  This is extremely stable, and takes extra energy to dusturb.  Conversely, Se has four in the 4p orbitals, meaning one extra--by losing this, it gets the more stable configuration acheived by neutral As.  the stability of the Se ion makes the required energy less, and this explains the local reversal of the ionization energy trend moving left to right.
458583
aluminum has 3 valence electrons