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What is a positive ion?
cation
What is a negative ion?
anion
What is an ionic bond?
The electrostatic attraction between a cation and an anion
What determines the charge of an ion?
how many electrons are lost or gained
What is the formula for an Ammonium ion?
NH4 +
What is the formula for a Silver ion?
Ag+
What is the formula for a Hydrogen ion?
H+
What is the formula for a Carbonate ion?
CO3 2-
What is the formula for a Sulfate ion?
SO4 2-
What is the formula for a Nitrate ion?
NO3-
What is the formula for a Phosphate ion?
PO4 3-
What is the formula for a hydroxide ion?
OH-
What are the properties of ionic compounds?
In general, ionic compounds form hard, brittle crystals that have high melting points.
Why can ionic compounds only conduct electricity in a solution or when molten?
The ions are free to move in an electrolyte and can carry current.
What are ions that do not participate in the reaction known as?
Spectator ions
What is different about the way an ion's electronic structure is shown?
It is drawn in square brackets?
What is a molecule?
a particle made of two or more atoms held together by covalent bonds
What is a covalent bond?
sharing of electrons between atoms
What type of element can form covalent bonds?
Non-metals
What are intermolecular (van der Waals) forces?
Weak forces between molecules
How do intermolecular forces vary with size of the molecule?
The greater the size of the molecule the greater the strength of intermolecular forces.
Why do molecular substances have low melting and boiling points?
Molecules are attracted to each other by weak intermolecular forces. These require little energy to overcome and so molecular substances have low melting and boiling points.
Why do molecular substances not conduct electricity?
They are all electrically neutral
What is the empirical formula?
The simplest whole number ratio of atoms of each element in a compound
How can molecular substances be represented?
Dot and Cross, Displayed formula, Ball and stick, space-filling model
What is a polymer?
long chain of monomers (small molecules)
What are thermosoftening polymers?
A polymer with no bonds between polymer chains that softens and melts when heated
What are giant covalent substances?
a continuous network of atoms linked by covalent bonds
Why do giant covalent substances have high melting and boiling points?
Many strong covalent bonds will have to be broken
Why don't giant covalent structures conduct electricity? Are there exceptions?
Most do not contain delocalised electrons, however graphite is an exception.
What are delocalised electrons?
Electrons that are free to move around
What is metallic bonding?
Strong electrostatic attraction between cations and delocalised electrons
Describe the structure of a metallic substance
A lattice of positive metal ions, surrounded by delocalised outer electrons.
Why do metals have high melting points?
Because in order to overcome the strong metallic bonds large amounts are energy are required
Why can metallic substances conduct electricity?
Delocalised electrons are free to move and carry a charge through the lattice
Why are metallic substances malleable?
Layers of metal atoms can slide over each other while maintaining the metallic bonding
What are alloys?
A mixture of metal and another substance, usually another metal, in order to improve its properties
Why are alloys stronger than pure metals?
the different sized atoms distort the layers, meaning it is harder for the layers of metal ions to slide over one other
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