Classify That Matter!
A substance consists of only one type of atom. What is it?
Element.
A piece of paper is torn into smaller pieces. Physical or chemical change?
Physical change. Only size and shape change.
Which separation technique uses a porous barrier to separate an insoluble solid from a liquid?
Filtration.
What is the name for a vertical column on the periodic table?
Group or family.
Which state of matter has a definite volume but takes the shape of its container?
Liquid.
Is carbon dioxide (CO₂) an element, compound, or mixture? Explain.
Compound. It contains carbon and oxygen chemically bonded together.
Milk turns sour after being left out. Physical or chemical change?
Chemical change. New substances form during the reactions that cause souring.
Which separation technique can separate the different colored pigments found in ink?
Chromatography.
Identify the element in Period 2, Group 17.
Fluorine (F).
In which state of matter do particles have the greatest freedom of movement?
Gas.
A sample contains two substances that are evenly distributed throughout. What type of mixture is it?
Homogeneous mixture (solution).
A student observes a substance changing becoming white and bubbling, as it becomes a solid and then produces a gas after the two substances are mixed. Name TWO signs that suggest a chemical reaction occurred.
Color change and gas production.
You have a mixture of sand, salt, and water. What technique would you use first to remove the sand?
Filtration.
An element is in Group 1A and Period 4. Identify the element and its family.
Potassium (K); alkali metals.
When a gas changes into a liquid, is energy absorbed or released? What is this process called?
Energy is released; condensation.
A substance contains two elements chemically bonded together. Can it be separated by physical means? Why or why not?
No. A compound requires chemical means to separate its elements.
Explain why boiling water is a physical change even though heat is being added.
The chemical identity remains H₂O. Only the state changes.
A student wants to separate two liquids with different boiling points and collect both of them. Which technique should she use?
Distillation.
Identify the element in Period 3, Group 16. What family does it belong to?
Sulfur (S); oxygen family.
A substance changes directly from a solid to a gas. What is this process called, and is it endothermic or exothermic?
Sublimation; endothermic.
A sample contains salt dissolved in water, along with undissolved sand. Is it a pure substance, homogeneous mixture, or heterogeneous mixture? Explain.
Heterogeneous mixture. It contains a solution and a separate sand phase.
A student claims that dissolving sugar in water is a chemical change because the sugar disappears. Explain why she is incorrect.
Dissolving sugar is a physical change. Sugar molecules remain chemically unchanged and can be recovered by evaporating the water.
A student uses chromatography to separate the pigments in black ink. Why do the pigments travel different distances?
They have different attractions to the stationary phase and different solubilities in the mobile phase, causing them to travel at different rates.
An element is located in Group 18 and Period 3. Identify it and explain one characteristic shared by its family.
Argon (Ar). Noble gases are generally very unreactive.
A reaction is represented by: Reactants + energy → Products. What type of reaction is this? Explain what happens to the surroundings.
Endothermic. Energy is absorbed by the reaction from the surroundings, causing the surroundings to cool.