Elements, compounds and mixtures (copy)

State what is meant by the term element.

An element is a substance made of atoms that all contain the same number of protons and cannot be split into anything simpler.

True or False?

Nitrogen is an element.

True.

Nitrogen is an element.

True or False?

Water is an element.

False.

Water is a compound composed of hydrogen and oxygen atoms chemically combined.

State what is meant by the term compound.

A compound is a pure substance made up of two or more different elements chemically combined together.

True or False?

Compounds can be separated into their elements by physical means.

False.

Compounds cannot be separated into their elements by physical means.

What is a mixture?

A mixture is a combination of two or more substances (elements and/or compounds) that are not chemically combined.

What is the difference between a compound and a mixture?

A compound consists of two or more elements that are chemically combined, while a mixture consists of two or more substances that are not chemically combined.

True or False?

All substances can be classified as elements, compounds, or mixtures.

True.

All substances can be classified into one of these three types.

Classify the following as an element, compound or mixture:

• Air

• Ammonia, NH₃

• Chlorine, Cl₂

• Copper sulfate, CuSO₄

The classifications of the following are:

• Air = mixture

• Ammonia, NH₃ = compound

• Chlorine, Cl₂ = element

• Copper sulfate, CuSO₄ = compound

What is the difference between an element and a compound?

An element consists of only one element, while a compound consists of two or more elements that are chemically combined.

Is a copper wire an element or compound?

Copper wire is an element.

What is the difference between a pure substance and a mixture?

A pure substance consists of only one substance (this can be an element or a compound), while a mixture contains two or more different substances that are not chemically combined.

True or False?

Salt dissolved in water is a pure substance.

False.

A solution of salt dissolved in water is a mixture.

What is a pure substance?

A pure substance is a single element or compound that contains no other substances.

What does filtration separate?

Filtration separates an undissolved solid from a mixture of solid and liquid.

In terms of the solid (solute), what is important about the solvent?

It is important that the solid (solute) is more soluble in hot solvent than in cold.

Solute

The substance being dissolved

Solvent

The substance doing the dissolving

Solubility

The maximum amount of solute that can dissolve at given temperature

Homogeneous Mixture

A mixture that looks the same throughout: Particles appear uniform

Heterogeneous mixture

A mixture that looks different throughout. Appears not uniform

Solutions are

homogeneous mixtures