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Atomic Structure
11 questions By Tony R. Kuphaldt
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Question 4 of 11
The Greek word for amber (fossilized resin) is elektron. Explain how this came to be the word describing a certain type of subatomic particle (electron).
Reveal answerWhen a piece of amber is rubbed with a cloth, a static electric charge develops on both objects. Early experimenters postulated the existence of an invisible fluid that was transferred between the amber and the cloth. Later, it was discovered that tiny sub-atomic particles constituted this “fluid,” and the name electron was given to them.
Notes:This question provides a good opportunity to discuss the history of electricity, and how its understanding and mastery has dramatically changed peoples’ lives. Be sure to ask questions about Benjamin Franklin and the modeling of electricity as a fluid. Scientific discovery is often assisted by models, but may also be hindered by them as well. Franklin’s model of electricity as a fluid has done both (conventional versus electron flow notation)!
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Question 5 of 11
It is much easier to electrically “charge” an atom than it is to alter its chemical identity (say, from lead into gold). What does this fact indicate about the relative mobility of the elementary particles within an atom?
Reveal answerElectrons are much easier to remove from or add to an atom than protons are. The reason for this is also the solution to the paradox of why protons bind together tightly in the nucleus of an atom despite their identical electrical charges.
Notes:Discuss with your students the importance of this fact: that electrons may be added to or taken from an atom rather easily, but that protons (and neutrons for that matter) are very tightly “bound” within an atom. What might atoms behave like if their protons were not so tightly bound as they are?
We know what happens to the electrons of some atoms when substances are rubbed together. What might happen to those substances if protons were not as tightly bound together as they are?
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Question 6 of 11
Early scientific researchers hypothesized that electricity was an invisible fluid that could move through certain substances. Those substances “porous” to this “fluid” were called conductors, while substances impervious to this “fluid” were called insulators.
We now know what electricity is composed of: tiny bits of matter, smaller than atoms. What name do we give these tiny bits of matter? How do these particles of matter relate to whole atoms?
In terms of these tiny particles, what is the difference between the atoms of conductive substances versus the atoms of insulating substances?
Reveal answerThe tiny bits of matter that move through electrically conductive substances, comprising electricity, are called electrons. Electrons are the outermost components of atoms:
Although electrons are present in all atoms, and therefore in all normal substances, the outer electrons in conductive substances are freer to leave the parent atoms than the electrons of insulating substances. Such “free” electrons wander throughout the bulk of the substance randomly. If directed by a force to drift in a consistent direction, this motion of free electrons becomes what we call electricity.
Notes:It is worthy to note to your students that metallic substances - the best naturally-occurring conductors - are characterized by extremely mobile electrons. In fact, solid-state physicists often refer to the free electrons in metals as a “gas” or a “sea,” ironically paying homage to the “fluid” hypothesis of those early experimenters.
The specific details of why some atoms have freer electrons than others are extremely complex. Suffice it to say, a knowledge of quantum physics is necessary to really grasp this basic phenomenon we call “electricity.” The subject becomes even more complex when we turn to superconductivity and semiconducting substances.
Question 11 answer appears to be typed incorrectly. It should be the following: A = P + N.