Structure and Bonding

Give the 3 definition of an element, compound and a mixture

• Element = substance of two or more of the same type of atom

• Compound = substance made of two or more elements chemically combined

• Mixture = made of two or more substances not chemically combined

What is an ionic bond?

An ionic bond is the strong electrostatic forces of attraction between oppositely charged ions

How do ions form?

Ions form when a neutrally charged atom gains or loses electrons to become positively charged (cations) or negatively charged (anions)

Give the symbols and charged for special compounds of transition metals

• Nitrate = NO3 -

• Hydroxide = OH -

• Sulphate = SO4 2-

• Carbonate = CO3 2-

• Ammonium = NH4 +

Why don’t noble gases (atoms in group 8 form bonds)?

They have a full outer shell and therefore do not need to lose or gain electrons because they are already stable

Why do ionic compounds have high melting and boiling points?

High energy levels are required to break apart the many strong electrostatic forces of attraction between the oppositely charged ions.

What states do ionic bonds conduct electricity in and why?

Molten and gaseous states because there are mobile ions that can move through the substance and carry charge

What state do ionic bonds not conduct eletricity in?

Solid form because there ions are held too tightly together and are not mobile, therefore they cannot move to carry charge through the substance

Describe the structure of a giant ionic lattice

Regular 3D alternating arrangement of oppositely charged ions held together by strong electrostatic forces of attraction.

What is a covalent bond?

A covalent bond occurs where two non-metal atoms share a pair of electrons so that both can reach a noble gas configuration.

Describe the structure of diamond and its properties

Structure = one carbo atom is bonded to 4 other carbon atoms

Properties =

• High MP + BP (high energy levels need to break apart many strong covalent bonds

• Non conductor of electricity because there are no charged particles to carry charge

• Very hard (many strong bonds) = used as glass cutters, cutting tools

Describe the structure of graphite and its properties

Structure = one carbon atom bonded to three other atom in a tetrahedral structure

Properties =

• High MP + BP (many strong covalent bonds to break = high energy levels)

• Good electrical conductor ( has delocalised electrons to move and carry charge through structure)

• Soft and Slippery (layers can slide over one another) = good lubricant/sandpaper

Describe the structure of silicon (IV) oxide and its properties

Structure = One silicon atom is bonded to 4 other oxygen atoms which are in themselves bonded to 2 other silicon atoms in a tetrahedral formation

Properties =

• High MP + BP (many strong covalent bonds need to be broken = high energy levels)

• Not a good electrical conductor = (no charged particles to move and carry charge through structure)

• Hard (not as hard as diamond) = many strong covalent bonds in structure

• Uses = glass manufacturing, electrical insulator

Descrive a Giant Covalent compound

A large 3D network of many non-metal atoms held together by strong covalent bond

Describe simple molecules

A small, defined group of non-metal atoms held together by covalent compounds

Why do simple molecules have low mp + bp?

Though their covalent bonds are strong, the intermolecular forces holding the molecules together are weak and require little energy to be overcome.

Why don’t simple molecules conduct electricity?

There are no charged particles to carry charge through the structure

Why do diamonds and silicon(IV)oxide share similar properties?

All their atoms are held together by strong covalent bonds