Download Unit 4 Fact Sheet

Unit 4 Fact Sheet
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Bromine and mercury are the only 2 liquid elements
Elements can be split into 2 group: metals and non metals
(using zigzag line)
Metals conduct electricity, non metals do not conduct (except
carbon- graphite)
When metals conduct the outer electrons move from one atom
to the next
State symbols: s = solid, l = liquid, g= gas and aq= aqueous (in
solution)
Compounds can be ionic or covalent
Ionic compounds contain metal and non-metal elements
Covalent compounds contain only non metal elements
Ionic compounds contain ions
Ions are atoms with a charge
An ion is formed when atoms gain or lose electrons
Metals lose electrons and become positive
Non metals gain electrons and become negative
Atoms give away or gain electrons to become like the noble
gases because noble gases are very stable.
The attractive force between ions of opposite charge is known
as an ionic bond.
Ionic compounds are always solid at room temperature
Ionic solids exist as network/lattices of oppositely charged
ions
Covalent compounds can be solid, liquid or gas at room
temperature
Covalent compounds never conduct electricity
Ionic compounds do not conduct when are solid but do conduct
when they are melted or in solution.
Covalent bonding involves atoms sharing electrons. The 2
positive nuclei are held together by their common attraction
for the shared pair of electrons
A solute is a substance which can be dissolved in a liquid.
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A solvent is a liquid which dissolves other substances.
A solution is the mixture formed when a substance dissolves in
a solvent.
Electrical energy chemically changes a solution when it
conducts
A DC power supply must be used to identify the products
Electrolysis means breaking up a compound into its elements
using electricity
The metal is formed at the negative rod because metal ions
have a positive charge
The non-metal is formed at the positive rod because non
metals have a negative charge
Covalent compounds cannot be electrolysed as they do not
contain ions
Very reactive metals can be extracted from their compounds
by electrolysis
In a battery the energy change is chemical energy to electrical
energy
Batteries go flat when the chemicals are used up
Batteries are portable and expensive, the mains supply is cheap
but not portable.
Some batteries are rechargeable (eg lead acid battery)
An electrolyte is a liquid in which conduction takes place by
ions moving (it is needed to complete the circuit)
Electricity can be produced by connecting different metals
together (with an electrolyte) to form a cell.
The movement of the ions in the ion bridge is to provide ions to
complete the circuit
The colour of an ionic compound is related to the colour of the
positive and negative ions