The atomin number decreases by how many, when a beta decay occurs?
348825
Beta decay is when an electron is fired out from the nucleus. Since the nucleus doesn't inherently contain electrons, an Neutron has to change to a Proton+Electron first so that the electron can be fired out.\n\nthe Atomic number therefore increases by 1.\n\ne.g.\n\nC6 -> N7 + β
943071
3mm is more precise than the above answers. Beta radiation can be stopped by as little as 3mm of aluminium.
954316
parent : daughter ratio is 1 to 15 so 1/16 of the original atoms are present . After 500 megayears it would be about 1/2, 1000Ma about 1/4, 1500Ma about 1/8 and after about 2000Ma it would be 1/16. \n\nto get a parent-daughter ratio of 1 to 7 then 1/8 of the original atoms are still present so 3000Ma is 3 half-lives. \n\nBest of luck - Mike
885073
Radioactive decay is the set of various processes by which unstable atomic nuclei emit subatomic particles (radiation). Decay is said to occur in the parent nucleus and produces a daughter nucleus. This is a random process, i.e. it is impossible to predict the decay of individual atoms.
703814
211_____207_____4\n      Bi  -->__Tl +____a    (a helium nucleus) \n83_______81_____2
798055
First the answer 129p and 130n is incorrect.  There is no element 129 and if there were it would certainly have more than 130 neutrons.  I think you are missing a piece of information, that being the atomic number or identity of the element. There are a number of elements that have an isotope that has a mass number of 259.  The 259 is the number of neutrons plus protons.  If you know the identity of the element, then you know number of protons (atomic number) and you can calculate the number of neutrons.  For example, if the isotope is No-259 then Nobelium has 102 protons and isotope would have 259-102 = 157 neutrons.  The number of electrons in an atom is equal to the number of protons.
1089354
Whatever its atomic number is, would be the number of electrons. If it's an ion, then add for every negative value and subtract for every positive one.
957728
Well that's not exactly correct: Atomic radius decreases in the same period of the periodic table as we go from left to right, so it decreases even though the mass number increases. That is because the heavier atom has more protons in nucleus that exert stronger forces to the electrons of the outer shell.\n\nBut the radius increases in the same group as we go from top to bottom, so a heavier atom has a bigger radius.
57444
Alpha particles are particles that are emitted from radioactive elements.  An alpha particle is nothing more than 2 neutrons and 2 protons, the same thing as a helium nucleus.  If an atom goes through alpha decay, it loses 4 atomic mass units (2 neutrons + 2 protons=4 mass units) and two atomic number values-- the atomic number stands for how many protons there are, so when it goes through alpha decay and loses two protons, the atomic number goes down by two.
915684
Very roughly:  by comparing the ratio between a radioisotope and its "daughter product", and with the knowledge of the radioisotope's half-life, calculate the amount of time needed for the observed ratio to develop.\n\nIn short, if there is a 50-50 split between the radioisotope and its daughter product, one half-life has passed.
972738
The number of protons is equal to the number of electrons (unless it is an ion), but in this case they are equal. The atomic number is equal to the number of protons, and the mass number is the number of protons plus the number of neutrons.
194993
Maybe you are asking for Uranium decay?\n\nCheck this link  http://www.ieer.org/fctsheet/uranium.html
773257
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!
724861
For the first question, , I think C is the least correct.  Alpha and beta emissions are particles, not rays.  B is also suspect, because not all radioactive emiissions are both particulate and energy.\n\nFor your true/false question, the answer is FALSE.  An alpha emission reduces the atomic number by 2, and reduces the atomic weight by 4.
1154910
7 because atomcic number(# of protons)=mass number-# of nuetrons.
482427
The "atomic" number refers to the place in the periodic table which corresponds directly (is equal to) the number of protons. The mass number is a weighted average involving commonly found isotopes.
213411
Atomic Number 3\nhttp://www.jergym.hiedu.cz/~canovm/vyhledav/varianty/litva.gif