Atoms & Molecules
What is the tiny particle that makes up everything around us and is too small to see with just your eyes?
What is an atom?
What state of matter has a definite shape and definite volume?
What is a solid?
What is density? (short student definition)
What is the amount of mass in a given volume (mass per unit volume)
What is the difference between a mixture and a solution?
What is: A mixture is two or more substances that are mixed but each keeps its own properties; a solution is a special type of mixture where one substance is dissolved uniformly in another.
When water freezes into ice, is that a physical or chemical change?
Physical change.
A group of two or more atoms bonded together is called what?
What is a molecule?
What state of matter takes the shape of its container but has a definite volume?
Answer: What is a liquid?
If you drop two objects of the same size into water and one sinks while the other floats, what property is likely different?
What is density?
What happens to the properties of the substances when you form a solution?
What is: They may change (the solute dissolves, the solution has uniform properties) but the original substances may still exist chemically (just distributed).
What are two signs of a chemical change?
Chemical change.
If I have a molecule of water (H₂O), how many atoms are in that molecule?
What is three atoms? (2 hydrogen + 1 oxygen)
$300: What state of matter has no definite shape and no definite volume (it spreads out to fill a space)?
Answer: What is a gas?
Give an example of a material you could classify by its physical property of solubility.
sugar dissolves in water; oil does not dissolve as easily, etc.
What is concentration of a solution?
What is: The amount of solute compared to the amount of solvent (or the relative amount of solute vs solvent).
When you tear a piece of paper, what kind of change is that?
Color change, gas/bubbles, temperature change, new substance
True or false: Atoms in a molecule always stay completely still and never move.
What is false? (they are always moving/vibrating)
When ice (solid) melts into water (liquid), what change in particle spacing happens?
What is: the particles move farther apart / the structure loosens?
True or false: If an object is more dense than water it will float in water.
What is false? (if it’s more dense it will sink)
Name two factors that can affect how fast a solute dissolves in a solvent.
What are stirring/agitation, temperature change, particle size/surface area?
What happens to the total amount of matter when it changes form?
No – matter is conserved (stays the same total amount).
Name one way atoms/molecules are arranged differently in a solid versus in a gas.
In a solid the molecules are close together and vibrate in place; in a gas they are far apart and move freely.
If you heat a liquid and it becomes a gas, what process is that called? Also name the reverse process when a gas becomes liquid.
What is evaporation (or boiling) for liquid → gas, and condensation for gas → liquid?
Design challenge: You have to build a vessel that can carry dense marbles across water without sinking. Name two design features you might include.
use a wide flat bottom to displace more water / use a hollow body to reduce overall density / use lightweight materials for the hull, etc.
You have a mixture of sand and salt in water. How could you separate them using at least two steps?
What is: First filter or let sand settle to separate sand from the salt solution; then evaporate (or boil) the water to get the salt crystals.
Name one way you can tell a new substance has formed.
Cutting changes shape only; burning creates new substances like ash and gas.