Answer:
a process that involves rearrangement of the molecular or ionic structure of a substance, as distinct from a change in physical form or a nuclear reaction
Answer:
- <u>Tellurium (Te) and iodine (I) are two elements </u><em><u>next to each other that have decreasing atomic masses.</u></em>
Explanation:
The <em>atomic mass</em> of tellurium (Te) is 127.60 g/mol and the atomic mass of iodine (I) is 126.904 g/mol; so, in spite of iodine being to the right of tellurium in the periodic table (because the atomic number of iodine is bigger than the atomic number of tellurium), the atomic mass of iodine is less than the atomic mass of tellurium.
The elements are arranged in increasing order of atomic number in the periodic table.
The atomic number is equal to the number of protons and the mass number is the sum of the protons and neutrons.
The mass number, except for the mass defect, represents the atomic mass of a particular isotope. But the atomic mass of an element is the weighted average of the atomic masses of the different natural isotopes of the element.
Normally, as the atomic number increases, you find that the atomic mass increases, so most of the elements in the periodic table, which as said are arranged in icreasing atomic number order, match with increasing atomic masses. But the relative isotope abundaces of the elements can change that.
It is the case that the most common isotopes of tellurium have atomic masses 128 amu and 130 amu, whilst most common isotopes of iodine have an atomic mass 127 amu. As result, tellurium has an average atomic mass of 127.60 g/mol whilst iodine has an average atomic mass of 126.904 g/mol.
<span>In a chemical change, the molecular structure of a substance changes. I think this is right. I hope this helps.</span>
In order to find the mass of tin with the given volume of 5.5 L and density of 7.265, we will use the formula
Density = Mass / Volume
We will just multiply both sides of the equation by the volume and we will get:
Mass = Volume x Density
We can now solve the problem by substituting the given.
Mass = 5.5 L x 7.265 g/L
Mass = 39.96 g
Answer: there are 39.96 grams of tin
In a sample of pure calcium fluoride of mass 15.0 g, 7.70 g of calcium is present. First convert the mass into number of moles as follows:
Here, m is mass and M is molar mass.
Molar mass of Ca is 40 g/mol, putting the values,
Similarly, molar mass of 
is 78.07 g/mol thus, number of moles will be:
.
Thus, 0.1921 mol of have 0.1925 mol of Ca, or 1 mole of will have approximately 1 mole of Ca.
Now, mass of Ca needs to be calculated in 45.0 g of . Converting mass into number of moles first,
Thus, number of moles of Ca will also be 0.5764 mol, converting number of moles into mass,
Therefore, mass of Ca will be 23.06 g.
