giant covalent structures,ionic bonding/structure,metals and alloys,small molecules

list properties of giant covalent structures

high mp and bp,hard and strong,dont conduct electricity except graphite

Explain how a covalent bond holds two atoms together.

electrostatic force of attraction between shared pair of negatively charged electrons and both positively charged nuclei

why are metals good conductors of electricity?

-the delocalised electrons in the metal carry electrical charge through the metal

-Good conductors of thermal energy because energy is transferred by the delocalised electrons

why does giant covalent structures have High melting and boiling point?

The atoms are connected by strong covalent bonds that require a lot of energy to break.

ionic comppounds structure,properties

Ionic compounds have regular structures (giant ionic lattices)

held by strong electrostatic forces of attraction between oppositely charged ions

the forces act in all directions

high melting and boiling points- because a lot of energy is required to break the many strong bonds.

When melted or dissolved in water-ionic compounds conduct electricity because the ions are free to move and carry current.

-can’t conduct electricity when solid because the ions are fixed in place.

explain why something would have a high mp like sodium oxide

• what is it

• forces of attraction

• how much energy required

its a giant ionic lattice with strong electrostatic forces of attraction between oppositely charged ions so large amounts of energy are needed to break the bonds

-The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points.

why dotn small molecules conduct?

don’t conduct electricity,there are no free charged particles free to movea and no overall electric charge.

what are small molecules usually,with what mp and bp

small molecules -usually gases or liquids that have low boiling and melting points because they have weak intermolecular forces between the molecules broken in boiling or melting

why metals have high mp and bp ,metals have what structure,what type of strong bonding

● Metals have giant structures of atoms with strong metallic bonding.

what is the bp and mp of metals

metals have high melting and boiling points.

how can pure metals be bent and shaped?

atoms are arranged in layers in pure metal ,The layers of atoms in metals are able to slide over each other, so metals can be bent and shaped

why are alloys harder than pure metals

in alloys the different sized atoms distort the layers in the structure, making it harder for them to slide over each other. it has

no layers,diff sized atoms,disorted layers

So alloys are harder than pure metals.

what are polymeers and properties

Polymers ● Have very large molecules ● Atoms in the polymer molecules are linked to other atoms by strong covalent bonds ● Intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature

why would something have low bp? for e.g amonnia or iodine

(ammonia has) small molecule 1 ,(ammonia has) weak intermolecular forces (so) little energy is needed to break the intermolecular forces

Explain why hydrogen chloride is a gas at room temperature. Answer in terms of structure and bonding

hydrogen chloride is made of small molecules 1

(so hydrogen chloride) has weak intermolecular forces* 1

the (intermolecular forces) require little energy to overcome*

Explain why chlorine is more reactive than iodine

(chlorine’s) outer shell closer to the nucleus

(so) the chlorine nucleus has greater attraction for outer electrons / shell

(so) chlorine gains an electron more easily

predict state of matter

Substance: Water Melting point: 0°C (freezing point) Boiling point: 100°C If the temperature is below 0°C, water will be a solid (ice). If the temperature is between 0°C and 100°C, water will be a liquid. If the temperature is above 100°C, water will be a gas (steam).

Below the melting point: The substance is a solid. Between the melting point and boiling point: The substance is a liquid. Above the boiling point: The substance is a gas

Limitations of the simple mode

-no forces

-all particles are represented as spheres

- the spheres are solid

Give one limitation of using a dot and cross diagram

-doesnt show shape

-its 2D