Basic Electricity

Atomic Structure

11 questions By Tony R. Kuphaldt

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Question 1 of 11

Shown here is a simplified representation of an atom: the smallest division of matter that may be isolated through physical or chemical methods.

Inside of each atom are several smaller bits of matter called particles. Identify the three different types of “elementary” particles inside an atom, their electrical properties, and their respective locations within the atom.

Reveal answer

Neutrons reside in the center (“nucleus”) of the atom, as do protons. Neutrons are electrically neutral (no charge), while protons have a positive electrical charge. Electrons, which reside outside the nucleus, have negative electrical charges.

Notes:
Most, if not all, students will be familiar with the “solar system” model of an atom, from primary and secondary science education. In reality, though, this model of atomic structure is not that accurate. As far as anyone knows, the actual physical layout of an atom is much, much weirder than this!

A question that might come up in discussion is the definition of “charge.” I’m not sure if it is possible to fundamentally define what “charge” is. Of course, we may discuss “positive” and “negative” charges in operational terms: that like charges repel and opposite charges attract. However, this does not really tell us what charge actually is. This philosophical quandary is common in science: to be able to describe what something is in terms of its behavior but not its identity or nature.
Question 2 of 11

Different types of atoms are distinguished by different numbers of elementary particles within them. Determine the numbers of elementary particles within each of these types of atoms:

• Carbon

• Hydrogen

• Helium

• Aluminum

Hint: look up each of these elements on a periodic table.

Reveal answer

Each atom of carbon is guaranteed to contain 6 protons. Unless the atom is electrically charged, it will contain 6 electrons as well to balance the charge of the protons. Most carbon atoms contain 6 neutrons, but some may contain more or less than 6.

Each atom of hydrogen is guaranteed to contain 1 proton. Unless the atom is electrically charged, it will contain 1 electron as well to balance the charge of the one proton. Most hydrogen atoms contain no neutrons, but some contain either one or two neutrons.

Each atom of helium is guaranteed to contain 2 protons. Unless the atom is electrically charged, it will contain 2 electrons as well to balance the charge of the protons. Most helium atoms contain 2 neutrons, but some may contain more or less than 2.

Each atom of aluminum is guaranteed to contain 13 protons. Unless the atom is electrically charged, it will contain 13 electrons as well to balance the charge of the protons. Most aluminum atoms contain 14 neutrons, but some may contain more or less than 14.

While you’re researching the numbers of particles inside each of these atom types, you may come across these terms: atomic number and atomic mass (sometimes called atomic weight). Be prepared to discuss what these two terms mean.

Notes:
Be sure to ask your students what definitions they found for “atomic number” and “atomic mass”.

It is highly recommended that students seek out periodic tables to help them with their research on this question. The ordering of elements on a periodic table may provoke a few additional questions such as, “Why are the different elements arranged like this?” This may build to a very interesting discussion on basic chemistry, so be prepared to engage in such an interaction on these subjects if necessary.
Question 3 of 11

Of the three types of elementary particles” constituting atoms, determine which type(s) influence the following properties of an element:

• The chemical identity of the atoms (whether it is an atom of nitrogen, iron, silver, or some other element).

• The mass of the atom.

• The electrical charge of the atom.

• Whether or not it is radioactive (spontaneous disintegration of the nucleus).

Reveal answer

• The chemical identity of the atoms: protons.

• The mass of the atom: neutrons and protons, and to a much lesser extent, electrons.

• The electrical charge of the atom: electrons and protons (whether or not the numbers are equal).

• Whether or not it is radioactive: neutrons, although one might also say protons in some cases, as there are no known “table” (non-radioactive) isotopes of certain elements, the identity of an element being determined strictly by the number of protons.

Notes:
It never ceases to fascinate me how many of the basic properties of elements is determined by a simple integer count of particles within each atom’s nucleus.

In the answer, I introduce the word isotope. Let students research what this term means. Don’t simply tell them!