We can calculate the mass percent of an element by dividing its atomic mass by the mass of the compound and then multiply by 100:
% by mass of element = (mass of element/mass of compound) x100%
Impurities like n-eicosane with the molecular formula C20H42 could account for the low percent by mass of oxygen in the sample because it has a zero percent oxygen based on its compound formula which indicates that it does not have the element oxygen.
Answer:
He changed more than one variable at a time
Explanation:
If the atom is neutral (meaning, not charged) the number of electron is equal to the number of protons. The mass number of an atom is the sum of the number of proton and the number of neutrons. From the given above, the mass number of gallium is 31 + 39. The answer is letter D. 70.
Answer: He did not discuss about any of these.
Explanation: Dalton proposed some of the postulates for his atomic theory. They are:
1) Matter is made up of atoms which are not divisible.
2) Atoms of different elements combine in a fixed ratio to form compounds.
3) The atomic properties of given element are same including mass. This states that all the atoms of an element have same mass but the atoms of different elements have different masses.
4) No atoms are either created or destroyed during a chemical reaction.
5) Atoms of an element are identical in mass, size and other chemical and physical properties.
As it is visible from the postulates, he only discussed only about the atoms but not subatomic particles or isotopes.
