Question

1. *classify each particle above as an element, molecule, compound, or more than 1.

particle element, molecule, and/or compound? briefly explain your classification.

1. **the diagram represents the starting materials (reactant) and ending materials (products) after a change has taken place. determine if this was a physical or chemical change. justify your response.

key: ● = atom of element a, ○ = atom of element q
reactants product

1. **given the particle diagram representing four molecules of a substance. which particle diagram best represents this same substance after a physical change has taken place?

key: ○ = atom of one element, ● = atom of a different element
a. b. c. d.

Explanation:

1.

• First particle: It consists of two identical atoms. An element is made of one - type of atom, and a molecule is a group of two or more atoms bonded together. So it is an element and a molecule.
• Second particle: It has different types of atoms bonded together. A compound is a substance made up of two or more different types of elements chemically combined, and it is also a molecule as it has multiple atoms bonded. So it is a compound and a molecule.
• Third particle: Similar to the second one, it has different atoms bonded, so it is a compound and a molecule.

In the diagram, the starting materials (reactants) are two different di - atomic molecules (one of element A and one of element Q) and the ending materials (products) are new molecules formed by the combination of atoms of A and Q. A chemical change is a process in which one or more substances are changed into new substances with different chemical properties. Since new substances are formed with different chemical compositions, this is a chemical change.

A physical change does not change the chemical composition of a substance. The original substance has molecules composed of two different elements bonded together. Option a shows the same molecules just in a different arrangement, which is characteristic of a physical change. Options b, c, and d show different chemical combinations or separated atoms, which would indicate a chemical change.

Answer:

• First particle: Element, Molecule; Explanation: Composed of two identical atoms.
• Second particle: Compound, Molecule; Explanation: Different atoms are bonded.
• Third particle: Compound, Molecule; Explanation: Different atoms are bonded.

2.