Which sentence about the periodic table of elements is true?
Group of answer choices
All elements in period 2 are metals.
All elements in group 18 are metals.
All elements in period 4 are metals.
All elements in group 4 are metals.
All elements in group 4 are metals.
The correct sentence about the periodic table of elements is: "All elements in group 18 are metals."
To determine which sentence about the periodic table of elements is true, we can refer to the periodic table itself. The periodic table is a tabular arrangement of chemical elements that organizes them based on their atomic number, electron configuration, and recurring chemical properties.
First, let's understand the terms "period" and "group" in relation to the periodic table:
- A "period" refers to the rows in the periodic table, numbered from 1 to 7. Each period represents the energy level or electron shell in which the elements' electrons reside.
- A "group" refers to the columns in the periodic table, numbered from 1 to 18. Each group represents elements with similar chemical properties due to the same number of valence electrons.
Now, let's evaluate the given statements:
1. "All elements in period 2 are metals." This statement is false because period 2 of the periodic table includes nonmetals (e.g., oxygen and carbon), not just metals.
2. "All elements in group 18 are metals." This statement is false because group 18, also known as the noble gases, consists entirely of nonmetals.
3. "All elements in period 4 are metals." This statement is false. Period 4 consists of elements that are a mix of metals, nonmetals, and metalloids.
4. "All elements in group 4 are metals." This statement is true. Group 4 consists of elements known as the transition metals, including titanium, zirconium, and hafnium, which are indeed metals.
Therefore, the correct answer is: "All elements in group 4 are metals."