GED Science Extra Prep: Chemistry

The GED Science test will very likely contain questions related to the field of chemistry. The following practice questions test your understanding of one of the most important things that a high school chemistry student will learn about: the periodic table.

Practice Questions

Use the following information to help answer both questions.

The periodic table organizes elements based on their atomic structure. The periodic table has rows (called periods) and columns (called groups). The group tells you how many valence electrons the element possesses, whereas the period tells you how many energy levels the atom has. Here is a simplified periodic table showing the first three periods of the Group A elements:

1. How many valence electrons does a carbon atom (symbol C) have?

   A. 4 B. 6 C. 12 D. 18

2. Which of the following elements is the least chemically reactive?

   A. fluorine, based on its seven valence electrons B. neon, based on its Group 8 status C. lithium, based on its one valence electron D. sulfur, based on its six valence electrons

Answers and Explanations

1. The correct answer is A.

   The number of valence electrons is given by the group number. Carbon is in Group 4 and therefore has four valence electrons.

2. The correct answer is B.

   When an element reacts, it tries to gain a full number of valence electrons in its outer shell. Group 8 elements already have full outer shells and are therefore very unreactive.