Answer:
- The standard form of a chemical element is the natural mixture of several isotopes of the same element, which is atoms with the same number of protons but different number of neutrons, while an isotope is a particular kind of atom with a definite number of neutrons.
Explanation:
A <em>chemical element</em> is a pure substance formed by atoms with the same atomic number (number of protons). This is because it is the number of protons what identifies an element.
For example: oxygen is a chemical element, so oxygen is formed by only atoms of oxygen, and the atomic number of those atoms is 8, because every oxygen atom has 8 protons.
Nevertheless, some atoms of oxygen, may have different number of neutrons. Isotopes are different kind of atoms of the same element, which only differ in the number of neutrons. So, some atoms of oxygen will have 8 neutrons, other 9 neutrons, and other 10 neutrons (those are the stable isotopes of oxygen).
That difference in neutrons, is generally accepted that, does not modifiy substantially the chemical properties of the element, but the mass number. So, the isotopes with more neutrons wil be heavier, and the isotopes with less neutrons will be lighter.
- Mass number = number of protons + number of neutrons.
In general a chemical element is formed by a mixutre of isotopes of the same element.
With the principle quantum number being 2, the maximum number that can share this is 8. You can use the general formula 2n^2 to calculate this number (n=quantum level), or you can use the concept of quantum numbers (n, l, m, s) to justify this answer.
Out of
the following given choices;
A. increasing
the pH of the salt.
B. increasing
the surface area of the salt.
C. increasing
the pressure of the salt.
<span>D. increasing
the temperature of the salt.</span>
The answer is B. When a substance is reduced to smaller
sizes, its surface area to volume ratio increases. Therefore crushing barium
salts to smaller particles increase the surface area on which it reacts with
the acid. This consequently increases the rate of speed of the reaction.
- Dalton reported that seven pounds of Oxygen reacted with one pound of hydrogen to form water, but accurate modern experiment gives eight pounds to one.
- Lavoisier reported that water contains Oxygen 5.6 times more than hydrogen by weight.
- Dalton assumed that water contains 1 atom of oxygen and 1 atom of hydrogen and concluded that the relative weight of O must be 5.6 times as large as the H atom.
- By determining the relative mass we will be able to determine for example that one element has twice the mass of a second element.
