When you boil water, you aren't changing the elements. You're just making water vapor. However, when you burn paper, it becomes carbon (mostly). So physical changes will not change the substance, only chemical changes will.
Answer:
electron-electron repulsion
Explanation:
When electrons add into valence shell of neutral elements, the element assumes a negative oxidation state. With this, the number of electrons having (-) charges will be larger than the number of protons having positive (+) charges. As a result, the extra electrons repel one another (i.e., like charges repel) and a larger radius is the result.
In contrast, when cations are formed, electrons are removed from the valence level (oxidation) producing an element having a greater number of protons than electrons. The larger number of protons will function to attract the electron cloud with a greater force that results in a contraction of atomic radius and a smaller spherical volume than the neutral unionized element.
To visualize, see attached chart that shows atomic and ionic radii before and after ionization of the elements.
The closeness of a measurement to its true value is a measure of its Accuracy.
Answer: 2 (2 neutrons are produced).
Explanation:
1) In the left side of the transmutation equationa appears:
²³⁵U + ¹n →
I am omitting the atomic number (subscript to the leff) because the question does not show them as it is focused on number of neutrons.
2) The right side of the transmutation equation has:
→ ¹⁴⁴Ce + ⁹⁰Sr + ?
3) The total mass number of the left side is 235 + 1 = 236
4) The total mass number of Ce and Sr on the right side is 144 + 90 = 234
5) Then, you are lacking 236 - 234 = 2 unit masses on the right side which are the 2 neutrons that are produced along with the Ce and Sr.
The complete final equation is:
²³⁵U + ¹n → ¹⁴⁴Ce + ⁹⁰Sr + 2 ¹n
Where you have the two neutrons produced.
