Chemistry CC1 - CC4

What are the three states of matter?

• Solids

• Liquids

• Gases

Solids

Fixed shape and volume, particles can vibrate in place.

Liquids

Fixed volume, shape adapts to container, particles slide past each other.

Gases

No fixed shape of volume, particles move freely and rapidly.

Changes of state

• Melting - Solid to liquid

• Freezing - Liquid to solid

• Boiling/Evaporation - Liquid to gas

• Condensation - Gas to liquid

• Sublimation - Solid to gas without becoming a liquid

Mixtures

• Homogeneous - Uniform composition (e.g. saltwater)

• Heterogeneous - Non-uniform composition (e.g. sand and water)

Separation techniques

• Filtration - Separates insoluble solids from liquids

• Crystallization - Forms solid crystals from a solution

• Distillation - Separates liquids based on boiling points

• Chromatography - Separates substances based on their movement through a medium.

Purification of water

• Simple distillation - Used to purify water by boiling and condensing.

• Fractional distillation - Separates mixtures of liquids with different boiling points.

Atomic Structure - Atoms and elements

• Atoms - Basic unit of matter, consisting of protons, neutrons and electrons.

• Elements - Pure substances made of only one type of atom.

Subatomic particles

• Protons - Positive charge, found in the nucleus

• Neutrons - No charge, found in the nucleus

• Electrons - Negative charge, orbit the nucleus in the outer energy shells.

Atomic number and mass number

• Atomic number - The number of protons in an atom.

• Mass number - Total number of protons and neutrons within an atom.

Isotopes

Atoms of the same element with different numbers of neutrons.

The periodic table - Development of the periodic table

• Mendeleev’s Table - Arranged by atomic mass, left gaps for undiscovered elements.

• Modern periodic table - Arranged by atomic number.

Groups and Periods

• Groups - Vertical columns, elements have similar properties.

• Periods - Horizontal rows, properties change progressively across a period.

Metals and Non-metals

• Metals - Left side of the periodic table, good conductors of heat and electricity.

• Non-metals - Right side of the periodic table, poor conductors.

Trends in the periodic table

• Reactivity - Varies across periods and groups.

• Atomic size - Decreases across a period, increases down a group.

• Ionization Energy - Energy required to remove an electron, increases across a period, decreases down a group.