Okay so I got this assignment that we're supposed to study and prepare for our final with it. But i have a problem. I don't remember some of this stuff! Final Week is coming up and i need to understand this stuff! If you guys could help, I'd be so thankful.
Here's the question: An atom in an excited state has an electron configuration of 2-7-2.
a) Explain in terms of subatomic particles, why this excited electron is electrically neutral.
b) Write the electron configuration of this atom in the ground state.
Different Problem: Explain, in terms of subatomic particles, why the radius of a chloride ion is larger than the radius of a chlorine atom.
THANKS GUYS! ;)
Here's the question: An atom in an excited state has an electron configuration of 2-7-2.
a) Explain in terms of subatomic particles, why this excited electron is electrically neutral.
b) Write the electron configuration of this atom in the ground state.
Different Problem: Explain, in terms of subatomic particles, why the radius of a chloride ion is larger than the radius of a chlorine atom.
THANKS GUYS! ;)
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I don't know what they've been teaching you. "2-7-2" is a bit archaic for an electron configuration. I've been teaching chemistry for 40 years, and I've never taught "shells" as electron configuration. I suppose you mean that there are two electrons in the 1st energy level and 7 in the second, and 2 in the third. Since the second energy in its ground state is filled when it has 8, that must mean that 1 electron was promoted from the second energy level to the third. There is a total of 11 electrons which means that if the atom was a neutral atom it would be an atom of sodium. The actual electron configuration of sodium is 1s2, 2s2 2p6, 3s1. The excited state you refer to would be 1s2, 2s2 2p5, 3s2. The problem is that there would never be such an excited state for sodium. The ionization energy of sodium is less than the energy needed to promote an electron from the 2p to the 3s, and so you would never see an excited state of 1s2, 2s2 2p5, 3s2, or 2-7-2.
There is actually no way to know that the excited atom is electrically neutral unless you knew the number of protons in the nucleus. Therefore, you can't really explain why it is neutral, because it may not be.
The ionic radius of Cl- is greater than the atomic radius because there has been added another electron to the 3p sublevel. Therefore, there is additional electron repulsion without a corresponding additional positive charge in the nucleus. Additional repulsion means that the electrons get farther apart and the ion gets bigger.
There is actually no way to know that the excited atom is electrically neutral unless you knew the number of protons in the nucleus. Therefore, you can't really explain why it is neutral, because it may not be.
The ionic radius of Cl- is greater than the atomic radius because there has been added another electron to the 3p sublevel. Therefore, there is additional electron repulsion without a corresponding additional positive charge in the nucleus. Additional repulsion means that the electrons get farther apart and the ion gets bigger.