Atomic Mass

The element that has the closest mass to 89 is Yttrium(88.91).

Well, two times four is eight, which would be oxygen.

The mass number is the sum between the number of protons and the number of neutrons in the nucleus of an isotope. The mass number is always a whole number.

You are probably getting confused between mass number, atomic weight and atomic number.

But if you think to atomic weight the answer is:

1. For example, chlorine has a listed atomic weight of 35.453. This is not, however, the mass of every chlorine atom. It is the "average" mass of a chlorine atom. There are two stable isotopes of chlorine, namely 35Cl and 37Cl which exist in the world at the corresponding percentages: (75.78%) and (24.22%). Since roughly one quarter of chlorines have 2 more amu, it makes sense that the atomic weight given is almost 35.5, which would be one quarter of the difference between 37 and 35. It is important to note again, however, that this is an average and not the mass of any actual chlorine atoms. (Also to note, there are other forms of chlorine in very minimal quantities which shift the number slightly, but not noticeably.)

2. Another important cause is the mass deffect (due to the binding energy of nucleons).

No, the element with the largest atomic mass is not always present in the highest percentage by mass in a compound. The percentage by mass of an element in a compound is determined by its atomic mass and the total mass of the compound. The composition of a compound can vary based on the number of atoms of each element present.

The atomic mass of an element is determined by the sum of the protons and neutrons in its nucleus. Beryllium has 4 protons and typically 5 neutrons, resulting in a total of 9 nucleons (protons + neutrons). This is why its atomic mass is 9 instead of 8.

The mass of the proton is a little greater than 1 amu:

The atomic mass subtracting the number of protons is equal to the number of neutrons in an atom. Neutrons help stabilize the nucleus and contribute to the overall mass of the atom without affecting its chemical properties.

Bromine is a non metal element. Atomic mass of it is 80.

Expressing atomic mass against a standard allows for uniformity and comparability between different elements. By using a standard reference point, such as carbon-12, scientists can accurately measure and compare the relative masses of different elements. This ensures consistency in scientific experiments and calculations.

The relative atomic mass of electrons is considered negligible, as they are much lighter than protons and neutrons. Protons and neutrons each have a relative atomic mass of approximately 1, as they are found in the nucleus of an atom and contribute to its overall mass.

Cobalt has a lower atomic mass than lead. The atomic mass of cobalt is approximately 58.93 g/mol, whereas the atomic mass of lead is about 207.2 g/mol.

As atomic mass increases, the number of protons and neutrons in an atom's nucleus also increases. This leads to a stronger nuclear force, which can make the nucleus less stable. Additionally, larger atoms may have a higher ratio of neutrons to protons, leading to greater instability due to the repulsive forces between positively charged protons.

Protons - 35

Neutrons - 43

Atomic Number - 35

Electrons - 35

The atomic mass of an element is found on the periodic table. It is the weighted average mass of all the isotopes of that element. Without more information, it's not possible to provide a specific value for the missing element's atomic mass.

I would expect the atomic mass of ekasilicon (silicon in the 14th element group of the periodic table) to be around 72 amu, as it is located in the same group as silicon. The atomic mass of an element is determined by averaging the isotopic masses of its naturally occurring isotopes, weighted by their abundance.

The numbers of protons and electrons in any neutral atom are the same as the atomic number, 13 for aluminum. The number of neutrons varies by isotope and can be found by subtracting the atomic number from the atomic mass number. One isotope is Al-27, in which there are 14 neutrons.

The atomic mass of magnesium is 24 because it is a weighted average of the isotopes of magnesium found in nature. The most abundant isotopes of magnesium are Magnesium-24, Magnesium-25, and Magnesium-26, with natural abundances of approximately 78.99%, 10.00%, and 11.01% respectively. The atomic mass takes into account both the mass and relative abundance of each isotope.

The relative mass of a neutron compared with a proton is one.

261 amu.

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The most stable isotopes of rutherfordium are:

- atomic mass of 265Rf: 265,116 700

- atomic mass of 267Rf: 267,121 530

Masses after IUPAC recommendations, 2009.

The atomic number of lead is 82. The number of neutrons in an isotope is always the difference between the isotopic mass number and the atomic number. In this instance, 206 - 82 = 124.

The atomic mass of an element is determined by the number of protons and neutrons in its nucleus. Protons and neutrons have almost the same mass and contribute to the overall mass of the atom. Electrons, on the other hand, have negligible mass compared to protons and neutrons and do not significantly affect the atomic mass.

The inner transition metal with an atomic mass of approximately 167.26 is Erbium (symbol: Er, atomic number: 68).

The atomic mass of oxygen (O) is approximately 16 atomic mass units.

The formula unit of sodium chloride has the formula NaCl, showing that each molecular unit contains one atom of each of its constituent elements. Therefore, the mass of the formula unit is 23 plus 35 or 57 amu. Each amu for a compound contains Avagadro's number of molecules. Therefore, the answer to the problem is about (15/57) X 6.022 X 1023 = 4.3 X 1022.

One needs to know the proportion of each isotope in the substance under question. If these four proportions are c_i where i ranges from 1..4, and the atomic masses are m_i, then the result is:

<m> = \sum_{i=1}^4 m_i \times c_i

or,

<m> = m_1 x c_1 + m_2 x c_2 + m_3 x c_3 + m_4 x c_4

where <m> is the average mass.

Remember that m_i are numbers which are proportions, so for, say, 13%, you should use 0.13

As an example, let's look at oxygen isotopes. Oxygen has three isotopes. The average weight calculated this way is:

<m> = 16 x 0.9976 + 17 x 0.00039 + 18 x 0.00201

<m> = 16.004

However, the reported average weight on this page is 15.9994amu. The reason there is a discrepancy here is because O16 does not have an atomic weight of 16amu due to mass loss through nuclear binding, and it is slightly less than 16. Pursuing that question is outside the scope of this answer, and this is not your question because you are given the masses of the isotopes. But the one missing piece are the relative amounts, c_i. Those seem to be pretty easy to get if you know the element, using wikipedia.