Michael B. answered • 07/19/14
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Doctor Loves to Teach Computer, Statistics
This question is not clear. Can you explain it a little differently?
OK, given your first comment, there is still something important missing. In a battery, elements do not flow at all, electrons do. They leave one substance and travel through a circuit to the other. Do a search for a simple explanation of how batteries work and get that issue firm in your mind first. Then, if the question is which direction electrons flow between Zinc and Magnesium, you might refer to the periodic table (though that alone probably isn't enough, so perhaps that's not actually the question).
L O.
that is why I am confused is about the flow.
this is the question.
If you had a battery which contained the elements magnesium (Mg) and zinc (Zn), in which direction would the current flow
a. from the magnesium to the zinc
b. from the zinc to the magnesium
c. from the magnesium to magnesium
d. from zinc to zinz
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07/19/14
Michael B.
Ah, now we're doing better! They're asking which direction current would flow, not how it flows from Zn to Zn.
The basic question is which element attracts electrons more, magnesium or zinc? That attraction is called the electronegativity. The electrons will flow toward the element that attracts them more strongly. However, the twist is that the current does not mean the electron flow but its opposite, so the current flows away from the element that attracts the electrons most.
If you check the Wikipedia article on electronegativity, you'll see a picture of the periodic table colored according to the electronegativity of each element. Elements on the lower left attract electrons the least, and those on the upper right the most. You can compare Mg and Zn and see which way the electrons will flow.
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07/19/14
L O.
so if it is the opposite then according to the periodic table it would be from zinc to the magnesium
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07/19/14
Michael B.
Right. The electronegativity of Zn is 1.65 and of Mg is 1.31, so zinc sucks the electrons from magnesium and the current goes toward magnesium; that's the same as saying that the positive "end" of the battery will be zinc and the negative end will be the magnesium.
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07/19/14
L O.
thank you very much because just by physically looking at the periodic table it would be easy to pick Mg to Zn
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07/19/14
Michael B.
Yes, though now that you know what to look for, you'll see that with only a couple of odd exceptions (and hydrogen, of course) everything in the first two columns of the periodic table is less electronegative than everything else. They're the atoms that really don't care that much about those extra one or two electrons in their unfilled outer shells.
You're welcome!
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07/19/14
L O.
07/19/14