Chemical Changes
What is a chemical change?
A change that produces one or more new substances with new chemical properties.
What component of the atom has a positive charge?
Proton
What is the formula for density?
Density = mass/volume.
What is the pH range for acids?
0-6
What is an element?
A pure substance consisting of one type of atom.
Give an example of a chemical change
Burning wood, rusting iron, or baking a cake (answers will vary)
What are the two main components of an atom's structure?
Nucleus & Electron cloud
If an object has a mass of 10 grams and a volume of 2 milliliters, what is its density?
5 g/mL
Name a common household acid
Vinegar or lemon juice
Give an example of a compound
Water (H₂O), sodium chloride (NaCl), etc.
What are 3 signs of a chemical reaction?
Color change, temperature change, gas production, or formation of a precipitate.
What subatomic particle is located in the nucleus and has no charge?
Neutron
What are the units commonly used for density?
Grams per milliliter (g/mL) or grams per cubic centimeter (g/cm³)
What is the pH range for bases?
8-14
What is a homogeneous mixture?
A mixture with a uniform composition throughout.
What is the difference between a reactant and a product in a chemical reaction?
Reactants are substances that start a chemical reaction, and products are substances that are produced in the reaction.
If we have a copper ion with a charge of +1, how many electrons does it have?
28 electrons
Why do steel ships float but solid steel blocks sink?
Because the ship's average density, including the air inside it, is less than the density of water
What is the pH of a neutral substance?
7
Give an example of a heterogeneous mixture
Sand and water, trail mix
What is a precipitate, and how can it indicate a chemical change?
A precipitate is a solid that forms from a solution during a chemical reaction. It indicates a chemical change because it signifies that new substances with different properties have been produced
How many protons, neutrons, and electrons does a neutral calcium atom have if its atomic number is 20 and its mass number is 40?
20 protons, 20 neutrons, and 20 electrons
How does temperature affect the density of most substances?
Most substances expand when heated, decreasing their density.
What happens when an acid and a base are mixed together?
They neutralize each other, often producing water and a salt
What is the difference between a compound and a mixture?
A compound consists of two or more elements chemically bonded together, while a mixture is a combination of two or more substances that are not chemically bonded and can be separated physically.