Review of Pure Substances and Mixtures

These flashcards cover key concepts from the lecture notes on pure substances, mixtures, ionic bonding, metallic bonding, and covalent bonding.

What defines a pure substance?

Contains only one type of particle.

What are the two categories of pure substances?

Elements and compounds.

Give an example of a compound.

Water (H₂O).

What is a mixture?

A substance made up of two or more pure substances.

What are heterogeneous materials?

Non-uniform mixtures that contain physically separate materials.

What are homogeneous materials?

Materials that have a uniform composition.

What can pure substances be used for?

To identify and separate the components of a mixture based on their distinct properties.

What are physical properties?

Properties that can be determined without changing the chemical composition of the substance.

Give an example of a physical property.

Melting point.

What characterizes chemical properties?

The ability of a substance to react to form new substances.

What happens in a chemical change?

The chemical composition is changed and a new substance forms.

What is ionic bonding?

The process where metals lose electrons to form cations and non-metals gain electrons to form anions.

How do metallic bonds form?

Positive ions are arranged in a lattice surrounded by a 'sea' of delocalised electrons.

What general properties do metals exhibit?

They are lustrous, good conductors of heat and electricity, malleable, and ductile.

What is the difference between covalent network lattices and covalent layer lattices?

Network lattices form 3D structures whereas layer lattices consist of layers held by weaker forces.

How do covalent layers conduct electricity?

Graphite can conduct electricity because one electron from each carbon atom becomes delocalised.

What are lone pairs in covalent bonding?

Electrons that are paired up but not participating in bonding.