STATES OF MATTER
I have a definite shape and a definite volume. My particles are closely packed and mainly vibrate in place. What state of matter am I?
Solid
What phase change occurs when ice turns into liquid water?
Melting
What is the basic unit of an element that retains the identity of that element?
Atom
A pure substance contains only one type of atom. What is it called?
Element
Is distilled water a pure substance or a mixture?
Pure substance
I have a definite volume but take the shape of my container. What state of matter am I?
Liquid
What phase change occurs when liquid water becomes water vapor?
Vaporization/Evaporation
What do we call two or more atoms that are chemically bonded together?
Molecule
A pure substance contains two or more different elements chemically bonded together. What is it called?
Compound
Is saltwater a pure substance or a mixture?
Mixture
I have neither a definite shape nor a definite volume. My particles are far apart and move freely. What state of matter am I?
Gas
Water droplets form on the outside of a cold glass. What phase change is occurring?
Condensation
Is O₂ an atom, a molecule or an element?
Molecule
Is carbon dioxide (CO₂) an element or a compound?
Compound
A sample contains only CO₂ molecules. Is it a pure substance or a mixture?
Pure substance
A student pours water from a glass into a bottle. The amount of water remains the same, but its shape changes. What property of liquids does this demonstrate?
Liquids have a definite volume but no definite shape.
A substance changes directly from a solid into a gas without becoming a liquid first. What is this process called?
Sublimation
A particle contains one oxygen atom and two hydrogen atoms chemically bonded together. What is it?
A molecule of a compound, H₂O.
Why is water (H₂O) classified as a compound rather than an element?
Because it contains two different elements, hydrogen and oxygen, chemically bonded in a fixed ratio.
A container contains oxygen molecules (O₂) and nitrogen molecules (N₂). Is the sample a pure substance or a mixture?
Mixture
Two samples contain the same number of particles. Sample A has particles packed closely together, while Sample B has particles spread far apart and moving freely. Identify the states of Sample A and Sample B.
Sample A — Solid;
Sample B — Gas
A gas changes directly into a solid without passing through the liquid state. What is this process called?
Deposition
A sample contains three O₂ molecules. Is the sample an element, compound, or mixture?
Element
A student says, “O₂ is a compound because it contains two atoms.” Is the student correct? Explain.
No. O₂ is a molecule of an element because it contains only one type of atom—oxygen. A compound must contain two or more different elements.
Two samples are shown:
Which sample is a pure substance and which is a mixture?
Sample A — Pure substance
Sample B — Mixture