What leads to the formation of gallstones?

What needed to be present in marine mud to form fossil fuels?

UkoKoshka [18]

When organisms and plants died and sank to the bottom of swamps and oceans, brown soil-like materials called peat are formed. Over millions of years, the peat became covered with sand, clay and other minerals and the peat is converted into layers of sedimentary rocks. After a long time, different type of fossil fuels are formed.

8 0

2 years ago

antimony has two naturally occuring isotopes, sb121sb121 and sb123sb123 . sb121sb121 has an atomic mass of 120.9038 u120.9038 u

Luda [366]

Considering the definition of atomic mass, isotopes and atomic mass of an element, sb121 has a percent natural abundance of 0.5726 or 57.26% and sb123 has a percent natural abundance of 0.4284 or 42.84%.

<h3>Definition of atomic mass</h3>

The atomic mass is obtained by adding the number of protons and neutrons in a given nucleus of a chemical element.

<h3>Definition of isotope</h3>

Isotopes are the chemical elements in which atomic numbers are the same, but the number of neutrons is different.

<h3>Definition of atomic mass</h3>

The atomic mass of an element is the weighted average mass of its natural isotopes.

This is, the atomic masses of elements are usually calculated as the weighted average of the masses of the different isotopes of each element, considering the relative abundance of each of them.

<h3>Percent natural abundance of each isotope</h3>

In this case, antimony has two naturally occuring isotopes, sb121 and sb123. You know:

sb121 has an atomic mass of 120.9038 u.
sb121 has a percent natural abundance of x.
sb123 has an atomic mass of 122.9042 u.
sb123 has a percent natural abundance of 1 -x (or, what is the same, the abundance is 100% - x%, since both isotopes form 100% of the element.)
Antimony has an average atomic mass of 121.7601 u

The average mass of antimony is expressed as:

121.7601 u= 120.9038 u x + 122.9042 u× (1 -x)

Solving:

121.7601 u= 120.9038 u x + 122.9042 u - 122.9042 u x

121.7601 u - 122.9042 u= 120.9038 u x - 122.9042 u x

(-1.1441 u)= (-2.0014) x

(-1.1441 u)÷ (-2.0014)= x

So, 1 -x= 1- 0.5716 → <u><em>1-x= 0.4284 or 42.84%</em></u>

Finally, sb121 has a percent natural abundance of 0.5726 or 57.26% and sb123 has a percent natural abundance of 0.4284 or 42.84%.

Learn more about average atomic mass:

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5 0

2 years ago

Pcl5 exist but ncl5 does not.why?

jeyben [28]

N is as electronegative as Cl is. So Cl doesnt react with O, N

6 0

2 years ago

What is the electron structure of a sodium atom?

Irina-Kira [14]

Answer:

1s2 2s2 2p6 3s1

Explanation:

All the elements in the periodic table, has an atomic number. This number tell us different things, such as number of protons, position in the periodic table among others.

One of the things that tell us the atomic number is the electron structure.

First, all elements begins always with 1s. This is because the first number indicates number of energy level which is in. This tell us, the period of the periodic table is the element, the s, is the type of orbital which the electrons are located. the s orbytal can only have 2 electrons max, and with the increasement of the atomic number, this electrons also increase.

Therefore for an element like Helium, (atomic number = 2) means that we have to begin with the 1s and put 2 electrons, to complete the atomic number. In this case, it would be 1s2.

When we surpass this number, we use another energy level, in this case, 2, and begin again with orbytal s. Then, when we surpass 2s2, we use now another orbytal, which is p. This is because we have more elements in the second period of the table, so we need another kind of energy levels to carry all the electrons. orbytal p can carry up to 6 electrons max, so for an element like Florine (Atomic number = 9), it's structure would be 1s2 2s2 2p5. As you can count the electrons, we have 2 + 2 + 5 = 9, we complete the atomic numbers and the electrons would be, the numbers of electrons located in the last energy level, in this case, the 2s and 2p, and it would be 7 electrons.

Now after this explanation, in the case of sodium (Na), the atomic number of sodium is 11, therefore, we need to count til 11 so:

[Na] = 1s2 2s2 2p6 3s1

As you can see, sodium is the first element of period 3 of the table, and we begin with the energy level 3. In your case it would be the last option you put.

8 0

3 years ago

How many moles of ethylene (C2H4) can react with 12.9 liters of oxygen gas at 1.2 atmospheres and 297 Kelvin?

Elena-2011 [213]

3 moles of oxygen will react with 1 mole of ethylene. Convert 12.9 L of oxygen to x moles of oxygen, then divide by three.

4 0

3 years ago

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