Essential Understandings
Learning Set 1:
Properties are unique characteristics that help identify a substance and distinguish one substance from another.
A substance is made of only one type of material (atoms or molecules) all the way through.
A mixture is made of more than one substance (or more than one type of atom or molecule).
Solubility is the capacity of one substance to dissolve in another substance.
Hardness and melting point are both properties of substances. Melting point is the temperature at which a solid substance starts to become a liquid.
Properties of a given substance are the same regardless of the amount of the substance.
Density is the mass in a set volume of a substance. It is calculated mathematically by determining the ratio of the mass of a sample to the volume it occupies.
Learning Set 2:
A chemical reaction happens when two or more substances combine in ways that make new substances form that have different properties from the beginning materials.
Burning is a chemical reaction in which a substance reacts with oxygen to form water and carbon dioxide.
A reactant is a starting substance in a chemical reaction. A product is the substance made by a chemical reaction.
Learning Set 3:
A chemical reaction occurs when substances interact and their atoms combine in new ways to form new substances. The new substances and the old substances are made of the same atoms, but those atoms are arranged in new ways. As a result, the new substances have different properties from the original materials.
A chemical reaction is the process of one substance breaking down or two or more substances interacting and their atoms combine in new ways to form new substances with different properties from the old substances.
Phase changes and mixing do not make new substances.
Atoms do not combine in new ways during a phase change or mixing.
Atoms cannot be created or destroyed. In a chemical reaction, the number of atoms stays the same; therefore matter and mass are always conserved.
Content Knowledge
Learning Set 1:
A substance is made of the same atoms or molecules throughout
Properties are unique characteristics that help identify a substance and distinguish one substance from another
A sample drawn from a larger portion has the same properties
A mixture is made of more than 1 substance
Properties provide evidence to determine how substances are the same or how they are different
Properties of a substance include solubility, melting point, hardness and density
Mass and volume are not properties because they change.
Learning Set 2:
Chemical reaction is a process in which old substances interact to form new substances with new properties
New substances are the result of atoms in an old substance rearranging to form new molecules
Atoms and molecules give substances their properties
Rearranging molecules and atoms result in a new substances.
Learning Set 3:
No matter how substances interact, the total mass of the system does not change.