What forms when atoms of two or more elements combine chemically?
a compound
100
What is a chemical formula?
a shorthand way to describe a compound
100
What do we use to describe, identify, and classify matter?
chemical and physical properties
100
What is the density of a material? How is it measured?
mass per unit volume.
it's measured by measureing the mass and the volume, the dividing.
100
Acids, bases, and salts are classes of compounds. How do we measure the strength of acids and bases?
With litmus paper and the pH scale
200
IS water a compound? What is it's chemical formula?
yes, H2O
200
What is carbon dioxide? What is it's chemical formula?
the gas you exhale when you are breathing. It is also in carbonated drinks. CO2
200
What is a physical property?
a property measured or detected by the sense. state, size, color, and odor.
200
Describe melting point.
Describe boiling point.
melting point is the temperature at which a solid melts to a liquid.
boiling point is the temberature at which a liquid changed to a gas.
200
What does pH stand for? What do acids show on the pH scale? How about bases?
potential of hydrogen.
acids have a pH value less than 7.
Bases have pH value greater than 7.
300
What is a chemical reaction and why is it important?
to forma compound, the atoms of the elements involved must take part in a chemical reaction. A chemical reaction is a process in which one or more substances are changed into one or more different substances.
300
What is sodium chloride commonly known as? What is the chemical symbol for it?
salt, NaCl
300
What are chemical properties?
ability of tendency of a material to change its chemical makeup.
300
Which of the following is NOT a physical property of matter?
conductivity, density, reactivity, solubility
reactivity
300
How doe acids and bases differ?
Acids taste sour, bases taste bitter. Acids turns blue litmus paper red, bases turn red litmus paper blue.
400
What is an important factor in all chemical reactions?
Energy
400
What are polymers? Name some examples of important polymers.
polymers are chain-like molecules made up of repeated units. Important ones includeL fats, proteins, carbohydrates, and DNA.
400
How does a substance change state?
at its melting or boiling point
400
Is density a chemical property or a physical property? Explain your answer.
Density is mass per unit volume, physical property.
400
How does sodium chloride compare with other salts?
Like most salts, NaCl is hard, brittle, has a low melting point and dissolves in water.
500
What does the subscript in a chemical formula represent?
the number of atoms in an element.
500
Identify three common compounds and their uses.
salt is used in cooking.
carbon dioxide is used in sodas.
glass is used in windows.
500
Describe the solubility of sugar in water.
sugar forms a solution when mixed with water, so it is soluble in water.
500
Don't swim outside during a thunderstorm! A lightning strike could send an electric charge through your body. Which physical property of water explains this safety tip?
Electrical conductivity; if lightning strikes the water, the electrical charge could travel through the water.
500
What is one product of a reaction between a strong acid and a strong base?
salt, acid, base, or indicator