Tiny But Mighty
What is the smallest basic unit from which all matter is made?
Atom
Gold is shiny. Physical or chemical property?
Physical
Air contains several gases evenly mixed together. What type of mixture is it?
Homogeneous
H₂O contains hydrogen and oxygen chemically bonded. Is it a compound?
Yes
What is the easiest way to separate the nuts from trail mix?
Sort/pick them out
Is everything you can see matter? Explain.
No. Matter must have mass and take up space; light, for example, is not matter.
A substance contains only ONE type of atom. What is it?
Element.
Iron can rust. Physical or chemical property?
Chemical
Trail mix contains visibly different ingredients. What type of mixture is it?
Heterogeneous
O₂ contains two oxygen atoms bonded together. Is it a compound?
No, because it contains only one element.
What property allows a magnet to separate iron from a mixture?
Magnetism
A student crushes a piece of gold into powder. Has the gold's chemical identity changed? Why or why not?
No; only physical properties like size and shape changed.
Two oxygen atoms bond together to make O₂. Is O₂ an atom or a molecule?
A molecule.
Wood is hard and difficult to bend. Name the type of property AND explain why.
Physical; you can observe/test it without creating a new substance.
Salt completely dissolves in water. You can no longer see separate parts. What type of mixture did you make?
Homogeneous
Which tells you more about a substance: saying it is a molecule or saying it is a compound? Why?
Compound, because it tells you the molecule contains two or more different elements.
You have salt water and want to collect the salt, not the water. What method should you use?
Evaporation
Salt water looks like one substance. Give two pieces of evidence that it is actually a mixture.
Salt and water are not chemically bonded; they can be physically separated.
CO₂ contains one carbon atom and two oxygen atoms. How many atoms and how many elements are present?
3 atoms, 2 elements
A scientist says, “This material melts at 80°C and burns when exposed to a flame.” Which observation is physical and which is chemical?
Melting point = physical; ability to burn = chemical
A student says, “If I can't see the different substances, it must be a pure substance.” Why is the student wrong?
Homogeneous mixtures look uniform even though they contain multiple substances.
A mystery molecule contains 6 atoms, but all 6 are carbon. Could it be a compound?
No; a compound must contain at least two different elements.
You have two mixed liquids with different boiling points and want to collect both separately. What method should you use?
Distillation
Two samples look completely identical. One is a pure substance and one is a homogeneous mixture. Why can't appearance alone tell you which is which?
Both can look uniform; you would need to determine whether they contain one substance or multiple substances that can be separated.
Explain why every compound is a molecule, but not every molecule is a compound.
Compounds contain different elements bonded together; molecules can contain atoms of the same element.
You are given an unknown metal. You may test its hardness, melting point, and ability to rust. Which test would actually change the identity of the substance?
Testing its ability to rust
You have two mystery mixtures. Mixture A looks identical throughout. Mixture B has visible chunks that can be sorted. Classify both.
A = homogeneous; B = heterogeneous
Substance X is made of identical molecules. Every molecule contains two nitrogen atoms and one oxygen atom. Is X an element, compound, mixture, or more than one? Defend your answer.
Compound; it contains different elements chemically bonded in a set ratio.
A mixture contains iron filings, sand, and salt. Design a method to separate all three.
Use a magnet for the iron → add water to dissolve the salt → filter out the sand → evaporate the water to recover the salt.
A mystery material is uniform throughout, cannot be separated by physical methods, and contains two different types of atoms chemically bonded in a fixed ratio. Classify it as specifically as possible.
A pure substance and a compound