VP #2: Differences Between Compounds, Molecules, and Mixtures

The oxygen in the air we breathe exist as

• CO2 (carbon dioxide)
• O3 (ozone)
• N2 (nitrogen)
• O2 (dioxygen)

What is a molecule?

• A mixture of different substances

• A group of two or more atoms bonded together

• A single atom

• A type of element

Which of the following is a compound?

• Helium

• Water

• Nitrogen

• Oxygen

What does the formula H2O represent?

• Two hydrogen atoms and one oxygen atom

• Two oxygen atoms and one hydrogen atom

• One hydrogen atom and two oxygen atoms

• Three hydrogen atoms

What is a key feature of compounds?

• They are not held together by chemical bonds

• They can be separated by physical methods

• They are always found in the same proportions

• They contain only one type of element

In compounds that have ionic bonds, the chemical formula is more of a indicator of the __________ of elements.

• chemical equation
• ratio

• structural formula
• molecular formula

Elements in compounds are always found in

• equal quantities
• variable amounts
• random proportions
• fixed ratios

How can mixtures be separated?

• By chemical reactions

• By physical methods like filtration

• By heating them

• By adding more substances