cant figure this out
please help
and if anyone knows the net charge of the nucleus, that wouldl be great
2006-09-12 12:56:03 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Atomic mass is a number that is relative to Carbon-12 = 12.000000.....
And many elements have isotopes, and thus different number of neutrons. So they calculate the average percentage of each isotope of the element, and then calculate the atomic weight using that answer, which is all relative to the isotope Carbon-12 = exactly 12.0000......
The net charge of a nucleus will always be positive. How MANY positive charges? To determine, multiple the charge on one proton by the atomic number of the element.
NOTE: the net charge on an undisturbed atom is zero, as electrons which are negative, cancel out the positive charge of the nucleus. Atomic number = number of protons = number of electrons. But you didn't ask that question. You asked about the nucleus all alone. Neutrons have zero charge.\
An "isotope" of an atom is one with a specific number of neutrons. All isotopes of a single element have the same number of protons, but different numbers of neutrons. If that is so, those are called isotopes of each other. Get it?
2006-09-12 18:36:12 · answer #1 · answered by MrZ 6 · 0⤊ 1⤋
the atomic mass of an atom is a fraction because it is a weighted average of all the isotopes of that element. An isotope is when an atom has more or less neutrons than the average amount of neutrons. The net charge of a nucleus is how ever many protons there are because there are only protons and neutrons in the nucleus and only protons have a charge.
2006-09-12 13:02:15 · answer #2 · answered by pt_of_vu 2 · 0⤊ 0⤋
A good question. Most elements are a mixture of different isotopes, which are chemically identical but their atomic weights are different. For instance ordinary hydrogen, with just a proton in its nucleus, has an atomic weight of 1, but deuterium has a neutron as well, so its atomic weight is 2. A sample of hydrogen obtained on Earth, say from water, is mostly H but with a few D atoms, so its atomic weight is a weighted mean of the two atomic weights; 1.008. The net charge of the nucleus is just the sum of the charges of the protons, as the neutrons have no charge.
2006-09-12 13:03:03 · answer #3 · answered by zee_prime 6 · 0⤊ 0⤋
The fractional mass number is due to the natural occurrence of isotopes, which are versions of the same element that have additional neutrons. The net charge of a nucleus depends upon the number of protons, which are positively charged. Usually, the numbers of electrons surrounding the nucleus equal the number of protons, thus making the atom's charge neutral. Neutrons do not possess a charge.
2006-09-12 13:01:00 · answer #4 · answered by strider89406 5 · 1⤊ 0⤋
The atomic mass listed on the periodic table is a weighted average of all the isotopes of each element. It is weighted on the relative amounts of each isotope available. So the mass is a decimal . In quantitative analysis you use all the decimal places. In high school you round off the mass to the closest whole number.
The charge on the nucleus is the number of protons, or the atomic number. (each proton has a positive charge)
2006-09-12 14:18:11 · answer #5 · answered by science teacher 7 · 0⤊ 0⤋
Most elements can occur in a variety of isotopes. Isotopes vary in the number of neutrons they have (having a different number of protons would make you a different element!). And because the difference between one isotope and another is pretty much indistinguishable chemically, the different isotopes tend to be pretty well mixed in nature.
So the fractional atomic masses listed take that into account. If 80% of Fakium has a mass of 42 and 20% of Fakium has a mass of 43, they'll list it as having a mass of 42.2. And because isotopes are so well mixed, usually any sample you use will have that mass, so it works out well.
Hope that helps!
2006-09-12 13:02:34 · answer #6 · answered by Doctor Why 7 · 0⤊ 0⤋
Most elements exist as isotopes of a particular elemnt; that is, they have the same number of protons, but different numbers of neutrons. Therefore, since a certain percentages of naturally occuring elements exist in the form of these isotopes, we must 'weight' the atomic mass to account for this. The result is an atomic mass that accounts for the 'average' mass of any given sample of that substance.
2006-09-12 17:29:59 · answer #7 · answered by trolling_on_dubs 1 · 0⤊ 0⤋
Because most elements in nature consists from isotopes. Take Chlorine (Cl):
It consists of 75% of an isotope with mass number 35 and 25% of an isotope with a mass number 37. If you take the mean value you get:
0.75*35 + 0.25*37 = 35.5 the atomic mass of Cl, not an integer
2006-09-12 13:01:42 · answer #8 · answered by Dimos F 4 · 1⤊ 0⤋
Because of isotopes (same atom with different mass). The mass listed represents the average or a reflection of the natural abundance of each isotope.
2006-09-12 13:53:51 · answer #9 · answered by jsn77raider 3 · 0⤊ 0⤋
Because the masses of the subatomic particles are;
Protons:1.00727 daltons
Neutrons:1.02741 daltons
Electrons: very small, doesn't really weigh much at all.
So a Hydrogen atom is 1 proton and 1 electron, thus it weighs around 1.00727 (in reality is 1.0079....). These measures account for the odd fractions that represent atomic masses.
2006-09-12 13:04:22 · answer #10 · answered by Eric D 1 · 0⤊ 0⤋