A certain element has 4 isotopes.40 percent of the atom have an atomic mass of 35. 60 percent have 37.?
546865
First, it seems to have only 2 isotopes.  \n\nYou need to take each mass and multiply by its percentage.  Then add the two resulting numbers together.  You then have the weighted average mass for the element, or average atomic mass.  This weighted average atomic mass is the one reported on the periodic table of elements.\n\n35 x 40%\n+\n37 x 60%
737924
You can figure it out.\n\nIf a neutral atom of zinc has an atomic number of 30, and a mass number of 65, then it has 30 protons, 35 neutrons, and 30 electrons.\n\nProtons and neutrons are found in the nucleus.\nSo, draw a circle. Write "30p+" and "35 n" inside it.\nThis represents the nucleus.\n\nIn Bohr's model, electrons orbit the nucleus at specific energy levels. The first level holds up to 2 electrons.\nThe second holds up to 8.\nThe third holds up to 8.\nThe fourth holds up to 18.\nWe use dots to represent electrons.\n\nDraw a ring around the nucleus.\nAdd two dots to the ring, usually at noon and 6:00.\n\nDraw another ring around the first one.  Draw eight dots: two at noon, two at 3:00, two at 6:00, and two at 9:00.\n\nContinue adding rings and electrons.\nYou should end up with twelve dots in the outermost ring.\n\n(Which doesn't correspond with the  Lewis diagram for zinc, but that's  another story....)
831094
36. >\n38. =\n40. >\n42. <\n44. <
776529
The number of protons in the fission product must be 92-55 = 37.  The number of neutrons must be 1+235-143-3 = 90.  Look up in the periodic table to see what element 37 is. It is virtually certain that 90 neutrons are too many for stability, and the product will be a beta emitter.
148855
Note that mass number is not the same thing as atomic mass; mass number is always a whole number, whereas atomic mass is always an average of the various isotopes of that element.  Lithium can have a mass number of 6, but it's more commonly 7, and its atomic mass is 6.941.
820564
Sodium has an Atomic Number of 11 and an Mass Number of 23 \n\nThis means an atom of Sodium has 11 Protons and therefore 11 electrons. \n\nSince the number of Protons + Neutrons is 23 and there are 11 Protons there must be 12 Neutrons
1141237
depends if it is 25.9% nitrogen by molar weight or total # of atoms
146629
The sodium atom has the atomic number of 11.  This means that it has 11 protons in the nucleus and 11 electrons in the space around it.\nThe most abundant isotope of sodium has an atomic weight of 23, this means that there are (23 - 11 = 12) 12 neutrons also in the nucleus.\nThe sodium atom has 11 protons, 12 neutrons and 11 electrons.\nThe sodium ion has a positive charge by loosing one of its electrons.  So the ion has 11 protons, 12 neutrons and 10 electrons.
172336
I believe the answer is Osmium. He is asking for number of neutrons, not number of protons. Take the atomic mass, (Os = 190.23) And subtract the number of protons it has (Os = 76), giving you an answer of 114.
186855
each one exerts 623N so overall it exerts 3742N.\n\ni dont care if its wrong (im too lazy to actually try to figure it out properly and check it n stuff)
1138448
Look on a periodic table.\n\nIt should be listed below the atomic number as a decimal value.  The mass number is an average mass (in atomic mass units) of an element, based on different isotopes.  It equals the number of protons + the number of neutrons in the nucleus.
921116
I'm not directly giving you the answers, you have to know how to do this stuff, but I'll give you the process to get to each.\n\n9: Americium and Curium (wikipedia!)\n\n10: Potassium ion wants to be like the noble gas closest to it (the one right before it), so it loses 1e- to get there and be K+.  If that's not a choice, then look for another ion, positive or negative, that adds up to the electronic configuration of the aforementioned noble gas. (1s2 2s2 2p6 3s2 3p6), 18 total e-'s...\n\n11: Mg is in column 2, things in the same period tend to be chemically similar.  Find the other one in the choices that's in that column\n\n12: U235 and U238 are isotopes, same atomic number, different weight.  If you change the number of protons, you change the atomic number, so that wouldn't be U anymore.  Changing electrons can make ions, but not change weight.  So different number of neutrons for the same element makes an isotope.\n\n13: Same explanation as above, it'll also be Hydrogen's atomic number because it's an isotope.\n\n14: shell 2 contains the 2s and 2p subshells.  2s can hold 2 because it's an s orbital.  2p can hold 2 per p orbital, and a p subshell has 3 p orbitals, so 6.  Total would then be...\n\n15: If an atom loses electrons, it's LOSING -1 per electron lost, so it's becoming more positive.\n\n16: Which element in that list only has 1s shell? Which one has a  stable ion as just a proton or with a configuration like Helium (1s2)?\n\n17: Inert elements are on the far right of the periodic table.  They are inert because they have 8 valence (outer shell) electrons (or 2 in Helium's case) so they can't take anymore and are stable.  Look at your periodic table or count up electrons for each of those atomic numbers.  Only one of them will have 8 in the outer shell...
107880
The atomic mass is equal (approximately) to the number of protons plus the number of neutrons.  The atomic number indicates the number of protons.  So atomic mass is atomic number plus the number of neutrons in the atom.
262869
Atomic Number: 47 \nAtomic Mass: 107.8682 amu \nMelting Point: 961.93 °C (1235.08 K, 1763.474 °F) \nBoiling Point: 2212.0 °C (2485.15 K, 4013.6 °F) \nNumber of Protons/Electrons: 47 \nNumber of Neutrons: 61 \nCrystal Structure: Cubic \n\nNumber of Energy Levels: 5 \n\nFirst Energy Level: 2 \nSecond Energy Level: 8 \nThird Energy Level: 18 \nFourth Energy Level: 18 \nFifth Energy Level: 1
409660
235 Uranium + 1 neutron --> 140 Cesium + 93 Rubidium + 3 neutrons
955650
Do you have the percentage abundances of the isotopes?\nE.g. for chlorine, it exists as 2 isotopes, namely Cl-37 and Cl-35.\nCl-37 (with 17 protons and 20 neutrons) has an abundance of 25% with Cl-35 (with 17 protons and 18 neutrons) has an abundance of 75%.\nThus average relative atomic mass of chlorine\n= [(25/100) x 37] + [(75/100) x 35]\n= 35.5\n\nHope this helps :)
106776
Hydrogen and helium, mostly. \n\n\nElement Number %\n\n--------------------------------------------------------------------------------\n in percent\nHydrogen 92.0\nHelium 7.8   \nCarbon 0.02 \nNitrogen 0.008\nOxygen 0.06\nNeon 0.01 \nMagnesium 0.003\nSilicon 0.004\nSulfur 0.002\nIron 0.003