Elements, Compounds, and Mixtures

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What is an element?

An element is a pure substance made up of only one type of atom.

Give an example of an element.

Examples include oxygen (O), gold (Au), and hydrogen (H).

What is a compound?

A compound is a substance formed when two or more elements chemically combine.

Give an example of a compound.

Water (H2O) is a compound of hydrogen and oxygen.

What is a mixture?

A mixture is a combination of two or more substances where each retains its own properties.

Give an example of a mixture.

Salt water is a mixture of salt and water.

How are compounds different from mixtures?

Compounds have elements chemically combined, while mixtures have substances physically mixed.

Can elements be broken down into simpler substances?

No, elements cannot be broken down into simpler substances by chemical means.

Can compounds be separated into their elements?

Yes, compounds can be separated into their elements through chemical reactions.

What process can separate a mixture of sand and water?

Filtration can separate a mixture of sand and water.

How can you separate a mixture of iron filings and sulfur?

You can use a magnet to separate iron filings from sulfur.

What is a homogeneous mixture?

A homogeneous mixture has a uniform composition throughout, like air.

What is a heterogeneous mixture?

A heterogeneous mixture has a non-uniform composition, like a salad.

How is a molecule related to compounds?

A molecule is the smallest unit of a compound that retains its chemical properties.

What state of matter are most metals at room temperature?

Most metals are solid at room temperature.





Test Your Knowledge

Select the correct option


1. What is an element?

An element is a pure substance made up of only one type of atom.

A molecule is the smallest unit of a compound that retains its chemical properties.

An element is a mixture of two or more substances.

An element is a solid at room temperature.

2. Give an example of an element.

Water (H2O)

Oxygen (O)

Salt water

Silver nitrate (AgNO3)

3. What is a compound?

A compound is a substance formed when two or more elements chemically combine.

A mixture is a combination of substances where each retains its properties.

A compound is a single type of atom.

A compound is a heterogeneous mixture.

4. Give an example of a compound.

Oxygen (O)

Water (H2O)

Sand

5. What is a mixture?

A mixture is a combination of two or more substances where each retains its own properties.

A mixture is formed when two or more elements chemically combine.

A mixture is a substance with only one type of atom.

A mixture can only be solid.

6. How are compounds different from mixtures?

Compounds have elements chemically combined, while mixtures have substances physically mixed.

Compounds can only exist as gases, while mixtures are liquids.

Compounds can be seen with the naked eye, mixtures cannot.

There is no difference.

7. Can elements be broken down into simpler substances?

No, elements cannot be broken down into simpler substances by chemical means.

Yes, elements can be broken down by physical means.

Yes, elements can be broken down by filtering.

Elements decompose on heating.

8. Can compounds be separated into their elements?

No, compounds are permanent.

Yes, compounds can be separated into their elements through chemical reactions.

Only if they are gases.

9. What process can separate a mixture of sand and water?

Distillation

Filtration

Chromatography

Evaporation

10. How can you separate a mixture of iron filings and sulfur?

Filtration

Using a magnet

By dissolving sulfur in water

By melting the mixture

11. What is a homogeneous mixture?

A homogeneous mixture has a uniform composition throughout, like air.

A homogeneous mixture is one where the substances remain distinct.

A homogeneous mixture has visible different parts, like sand and pebbles.

12. What is a heterogeneous mixture?

A uniform mixture like air.

Only liquids can be heterogeneous.

A heterogeneous mixture has a non-uniform composition, like a salad.

A mixture where gases are present.

13. How is a molecule related to compounds?

A molecule is the smallest unit of a compound that retains its chemical properties.

A molecule is always broken down in compounds.

Molecules are only present in elemental gases.

14. What state of matter are most metals at room temperature?

Most metals are solid at room temperature.

Most metals are liquids at room temperature.

Most metals are gases at room temperature.

Most metals are plasma at room temperature.