Biology 1406 Chapter 2

What coefficients must be placed in the following blanks so that all atoms are accounted for in the products? C6H12O6 —> ______ C2H6O —> CO2

2; 2

We can represent atoms by listing the number of protons, neutrons, and electrons for example, 2p+, 2n0, 2e- for helium. Which of the following represents the 18O isotope of oxygen?

8p+, 10n0, 8e-

What happens when two atoms form a chemical bond?

A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.

What does the term electron orbital describe?

An electron orbital describes a three-dimensional space where an electron can be found 90% of the time.

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

H2S

Which statement is true of all atoms that are anions?

The atom has more electrons than protons.

In the term trace element, the adjective trace means that

The element is required in very small amounts

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

The rates of the forward and reverse reactions are equal.

Compared with 31P, the radioactive isotope 32P has

one more neutron

The reactivity of an atom arises from

the existence of unpaired electrons in the valence shell