Chapter 6: Substances (Barsam)

Draw a carbon dioxide molecule.

• 
• O2 + C

• CO2 + H2O

• C + O2

Draw a water molecule.

• 
• CO2

• NaCl

• O2

Is a compound a pure substance or a mixture, and why?

• A compound is a mixture because it contains different elements.

• A compound is a pure substance because its composition is uniform at the atomic level.

• A compound can be either a pure substance or a mixture depending on its components.

• A compound is a pure substance because it can be separated into its elements by physical means.

Explain what an element's atomic mass is.

• Atomic Mass is the mass of the nucleus, which is the number of protons added to the number of neutrons.

• Atomic Mass is the total number of electrons in an atom.

• Atomic Mass is the weight of an atom in grams.

• Atomic Mass is the average mass of all isotopes of an element.

Explain the difference between a mixture and a compound.

• A mixture is a combination of substances that retain their individual properties, while a compound is a substance formed from two or more elements chemically bonded.

• A mixture is a pure substance with a uniform composition, while a compound is a combination of different substances that do not retain their properties.

• A mixture is always a solid, while a compound can be a solid, liquid, or gas.

• A mixture is formed through a chemical reaction, while a compound is a physical combination of elements.

Define 'molecule'.

• A molecule is a group of atoms bonded together.

• A molecule is a single atom.

• A molecule is a type of chemical reaction.

• A molecule is a large structure made of cells.

Draw the info box for the element Chlorine.

• 
• Atomic Number: 16
  Symbol: S
  Group: 16
  Period: 3

• Atomic Number: 18
  Symbol: Ar
  Group: 18
  Period: 3

• Atomic Number: 17
  Symbol: Cl
  Group: 18
  Period: 3

What is a solution?

• A solution is a heterogeneous mixture of two or more substances.

• A solution is a homogeneous mixture of two or more substances.

• A solution is a pure substance with a fixed composition.

• A solution is a mixture that cannot be separated by physical means.

What is the chemical formula for water, and what do the letters and numbers mean?

• H2O, where H is hydrogen and O is oxygen, meaning 2 hydrogens for every 1 oxygen.

• H2O, where H is helium and O is oxygen, meaning 2 helions for every 1 oxygen.

• H2O2, where H is hydrogen and O is oxygen, meaning 2 hydrogens for every 2 oxygens.

• H2O, where H is hydrogen and O is ozone, meaning 2 hydrogens for every 1 ozone.

How are homogeneous and heterogeneous mixtures different?

• Homogeneous mixtures have a uniform composition, while heterogeneous mixtures have distinct, separate components.

• Heterogeneous mixtures have a uniform composition, while homogeneous mixtures have distinct, separate components.

• Both homogeneous and heterogeneous mixtures have a uniform composition.

• Homogeneous mixtures are always solid, while heterogeneous mixtures are always liquid.