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.
Answer:
C The experiment shows that the red substance experienced a chemical change.
Explanation:
Apparently, adding heat caused the red substance to decompose into a gas and a metallic liquid. If it were simply a phase change, the original red substance could be expected to return when the temperature cooled. Because the substance apparently decomposed, it is clearly not an element. At no point in the experiment is there any evidence of a plasma being formed.
The observed decomposition is a chemical change.
- <u>Atoms</u>... and here's an atom joke to maybe make you laugh a little...
<em>Why can't you trust atoms?</em>
<u><em> - Because they make up everything!!!</em></u>
Answer:
1
Explanation:
An unknown element, X, is a nonmetal that contains seven valence electrons. Element X most likely forms <u>1 </u>covalent bond.
Nonmetals gain the electron to complete the octet and form anion. Consider the example of halogen.
When it combine with another halogen atom they form covalent bond. There are seven valance electrons in outer most orbital of halogen atom. By combining with other halogen atom they form one covalent bond and complete the octet.
For example:
Cl atom combine with other Cl atom and form Cl₂.
