Question

teks 8.6.a models of matter 8.6.a: explain by modeling how matter is classified as elements, compounds, homogeneous mixtures, or heterogeneous mixtures; matter is anything that has mass and takes up space. there are three major classes of matter: elements, compounds, and mixtures. an atom, the smallest unit of an element that maintains the properties of that element, is the basic building block for all three types of matter. atoms are combined in different ways to produce different elements, compounds, and mixtures. elements are made up of one or more of the same kind of atom chemically combined. they are pure substances that have definite physical and chemical properties. regardless of the amount of a pure substance present, it will always have the same properties because it is made up of one type of particle. elements are classified based on differences in their physical and chemical properties. broadly speaking, elements are classified as metals, nonmetals, or metalloids. - metals are generally shiny, conduct heat and electricity well, and can be shaped into thin sheets and wires. - nonmetals are not shiny and do not conduct heat or electricity well. - metalloids have some properties of both metals and nonmetals. the periodic table of elements is a tool used to arrange the over 100 known elements into groups that have similar properties. alexandra and maddy made an atomic model of a substance as shown alexandra thinks it’s an element, but maddy thinks it’s a compound. which statement explains why either alexandra or maddy is correct? - alexandra is correct because there are two atoms in each molecule, making it a compound. - alexandra is correct because there is only one type of atom in each molecule. - maddy is correct because there are two atoms in each molecule. - maddy is correct because all molecules are compounds.

Explanation:

To determine who is correct, we analyze the definitions:

• An element is made of one type of atom (either as single atoms or molecules with the same type of atom). A compound is made of two or more different types of atoms chemically combined.
• In the model, each molecule has two atoms, but they are the same type (since all molecules look identical in terms of atom type).
• Let's evaluate each option:
• First option: Says Alexandra is correct but claims two atoms make it a compound. This is wrong (compounds need different atoms).
• Second option: Alexandra is correct because there is only one type of atom in each molecule. This matches the definition of an element (molecules of an element can have multiple atoms of the same type, like \( \text{O}_2 \), \( \text{N}_2 \), etc.).
• Third option: Maddy is correct because two atoms in each molecule. But two atoms of the same type make it an element, not a compound. So this is wrong.
• Fourth option: Maddy is correct because all molecules are compounds. This is false (molecules of elements exist, like \( \text{O}_2 \)).

So Alexandra is correct because each molecule has only one type of atom.

Answer:

B. Alexandra is correct because there is only one type of atom in each molecule.