The reactivity of an atom arises froma. the average distance of the outermost electron shell from the nucleus.b. the existence of unpaired electrons in the valence shell.c. the sum of the potential energies of all the electron shells.d. the potential energy of the valence shell.

What are the six most important chemical elements of life?

In the term trace element, the adjective trace means thata. the element is required in very small amounts.b. the element can be used as a label to trace atoms through an organism's metabolism.c. the element is very rare on Earth.d. the element enhances health but is not essential for the organism's long-term survival.

Fill in the blanks in this concept map to help you tie together the key concepts concerning elements, atoms, and molecules.

We can be sure that a mole of table sugar and a mole of vitamin C are equal in theira. mass.b. volume.c. number of atoms.d. number of molecules.

Changing the _________ would change it into an atom of a different element.a. number of electrons surrounding the nucleus of an atomb. number of protons in the nucleus of an atomc. electrical charge of an atomd. number of neutrons in the nucleus of an atom

Add labels to the figure that follows, which illustrates the subatomic particles associated with a carbon atom.

Electrons .a. are negatively charged;b. along with neutrons make up the nucleus;c. are attracted to the negatively charged nucleus;d. are not involved in ionic bonds;e. all of the above are true

In what way does the need for iodine or iron in your diet differ from your need for calcium or phosphorus?