Pure Substances
What is a pure substance?
A material made of only one type of particle.
What is a homogeneous mixture?
A mixture that has a uniform composition throughout.
What is a heterogeneous mixture?
A mixture where the components are not uniformly distributed.
What do each box on the periodic table represent?
A different element.
What are physical properties?
Characteristics that can be observed without changing the substance.
Give an example of a pure substance.
Water (H₂O) or table salt (NaCl).
What is another name for homogeneous mixtures?
Solutions.
Give an example of a heterogeneous mixture.
Salad or gravel.
What are the three main categories of elements on the periodic table?
Metals, nonmetals, and metalloids.
Name a physical property of metals.
Answer will vary: conductors, malleable, lustrous, ductile, solid, low melting and boiling points.
How can you tell if a substance is pure?
It has the same properties and cannot be seperated.
What is an example of a homogeneous mixture?
Saltwater or air.
How can you tell a mixture is heterogeneous?
You can see and identify the different components.
What are rare Earth elements?
A group of 17 elements found at the bottom of the periodic table, important for technology.
Name a property of nonmetals.
Answers will vary: dull, brittle, insulators, mostly gases, low melting and boiling points.
What is the difference between an element and a compound?
An element is made of one type of atom, while a compound is made of two or more types of atoms chemically bonded.
How can you separate a homogeneous mixture?
By processes like evaporation.
What methods can be used to separate heterogeneous mixtures?
Filtration or handpicking.
Why are metals important to modern life?
They are used in construction, electronics, and transportation.
They are a semiconductor.
Why are pure substances important in science?
They have specific properties that can be used in experiments or applications.
Why is it difficult to see the individual particles in a homogeneous mixture?
The components are evenly distributed and not visible.
Why are heterogeneous mixtures common in everyday life?
Many natural materials consist of different substances mixed together.
How do nonmetals differ from metals in terms of physical properties?
Nonmetals are generally not shiny, poor conductors of heat and electricity, and can be gases or brittle solids.
Why is knowing the physical properties of elements important?
It helps in identifying, using, and understanding their applications in everyday life.