GCSE Chemistry: Ionic, Covalent and Metallic bonding

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