Access Student Page (includes Focus Words list and slides for the unit)homogeneous
adjective – (of mixtures) even, smooth, the same in every part
Salt water contains evenly distributed sodium and chlorine atoms, making it a homogeneous mixture. Can you think of another?
adjective – (of mixtures) uneven, lumpy, different in different parts
What foods do you eat that are heterogeneous mixtures?
noun—a combination of two or more substances
To get solid salt out of a saltwater mixture, evaporate the water molecules away by boiling it.
adjective— composed completely of a single substance and not mixed with any other material
H2O is a very poor conductor—but water is almost never pure in the real world.
noun – the rate of dissolved substance to solvent in a solution
As the water in salt water evaporates, what happens to the concentration of salt?
noun – a homogeneous mixture
Many people who wear contacts clean them with saline solution. Name a solution that you use in your daily life.
verb – to lower the strength of a solution by adding water (or other solvent)
Can you think of a substance that you would dilute by adding something other than water?
verb – to make one substance (a solute) disperse into another (a solvent), forming a solution
Very gradually, rain erodes and dissolves rocks, so that the runoff that flows into streams and rivers carries some sodium, chlorine, and other ions.
noun – noun – a pure substance (either an element or a compound)
Water is a chemical, but mud is a mixture of many chemicals.
adjective – having to do with chemicals and the transformations between chemicals
Flammability is a chemical property, because you can’t judge the flammability of a substance without burning it; and burning is a chemical change because the starting substances (like wood and oxygen) are transformed into new substances (like carbon dioxide, water vapor, and ash).
adjective— (used in contrast to “chemical”) having to do with properties of matter that don’t involve one substance changing into another
Density is a physical property, because you can measure the density of a substance without the substance undergoing a chemical change; and evaporation is a physical change because a substance retains its same chemical identity when it changes from a liquid to a gas.
noun – a substance made of definite proportions of two or more elements
Water is a chemical compound. Can you name the elements that combine to form water molecules?
noun – the ratio of mass to volume
How do differences in density help balloons float in the air?
noun – a state of matter, usually solid, liquid, or gas
What phase change takes place as snow melts?