Pure Substance
Any matter that has a fixed composition and definite properties
Element
A substance that cannot be broken down into simpler substances
Atom
The smallest particle that has the properties of an element
Compound
A substance made up of atoms of more than one element chemically bound together
Molecule
The smallest unit of a substance that exhibits all of the properties characteristic of that substance
Mixture
A combination of more than one pure substance
Heterogeneous mixture
Substances that are not uniformly mixed
Homogeneous mixture
Substances that are uniformly mixed
Immiscible solution
Describes two or more liquids that do not mix into each other
Miscible solution
Describes two or more liquids that are able to dissolve into each other in various proportions
Suspension
Heterogeneous mixture containing a liquid in which particles settle out
Colloid
A type of mixture with particles larger than those in soultions but not heavy enough to settle out
Solution
Homogenous mixture who's particles are so small they cannot be seen with a microscope
Tyndall effect
Scattering of light by colloidal particles
Distinguish between a pure substance and a mixture? Give two examples for each
Pure substance cannnot be separated. (Ex. Any element on the periodic table)Mixture can be separated. (Water & sand, salad, soup)
How is a compound similar to a homogeneous mixture? How is it different?
Similar: They are both made of more than one type of element/atom.
Different: A compound is chemically bonded unlike a homogeneous mixture.
Identify three elements and three compounds. How are they similar? How are they different?
Elements: O, Au, Ag
Compounds: H2CO3, H2SO4, CaSiO3
Similar: Both have elements and atoms
Different: Element is made up of the same atom and a compound has different types of atoms.
Why do the words "shake well before using" indicate that the fruit in a carton is a suspension? Why are these words not used on a milk container?
The fruit carton contains large particles of fruit that settle at the bottom of the container and would become a heterogeneous mixture. Milk is a homogeneous mixture because the particles in the milk are small enough and cannot be seen.
Compare the properties of Suspensions, Colloids, and Solutions
Suspensions: Large particles, settles out upon standing
Colloids: Medium size particles, Settles out upon standing, Scatters light
Solutions: Very small particles, Does not settle upon standing
How could you tell how many different elements are present in a chemical formula?
Every element in a chemical formula has a capital letter. (Ex. Ag)
How are atoms represented in a chemical formula?
Atoms are the capital letters in a chemical formula.
How are molecules represented in a chemical formula?
They are the subscript numbers
Physical property
Any characteristic of a material that you can observe without changing the identity of a substance. (Ex. Color, shape, size, density, melting point, and boiling point)
Chemical property
A change of one substance to another
Distillation
Process that can separate two substances in a mixture by evaporating a liquid and recondensing its vapor
Physical change
A change in size, shape, or state of matter in which the identity of the substance remains the same
Chemical change
Any characteristic of a material that you can observe that produces one or more new substances
Law of conservation of mass
The mass of all substances that are present before a chemical change equal the mass of all of the substances that remain after the change.
Explain why evaporation of water is a physical change and not a chemical change
The water is not changing into a different substance, the water is just changing its state of matter
Identify four physical properties that describe a liquid and a chemical property.
Physical: Viscosity, color, temperature, boiling point
Chemical: Linear coefficient of thermal expansion
Explain how the law of conservation of mass applies to chemical changes
During a chemical change matter cannot be created or destroyed it can just change its form.
Does the law of conservation of mass apply to physical changes? How can you test this for melting ice?
Yes, if you fold a piece of paper it still has the same mass. Put ice in a cup and let it melt until it turns into a liquid.