Chemistry ✿ Bonding, structure, and the properties of matter

how are ions formed?

when an atom loses or gains an electron

why are elements from groups 1, 2, 5 and 6 more likely to form ions?

• elements from groups 1 and 2 can easily lose an electron to gain a full outer shell

• elements from groups 5 and 6 easily gain an electron to gain a full outer shell

ionic bonding

• when a metal and non-metal reacts

• electrons are transferred

• caused by oppositely charged atoms

give 3 features of the structure of an iconic compound

• held together by strong electrostatic forces between oppositely charged ions

• regular lattice

• conductors ONLY when melted

why do ionic compounds have high boiling points?

due to strong electrostatic forces, they need more energy to be broken

covenant bonding

• when non-metal and metals react

• electrons are shared

metallic bonding

• when 2 metals react

• sharing delocalised electrons

give 4 features of a simple molecular substance

• usually gases or liquids

• low melting points and boiling points

• weak intermolecular forces between the molecules

• as molecules get bigger the higher their melting and boiling points will be

polymers

long chains of molecules joined by covalent bonds

give 3 features of a polymer

• large intermolecular forces

• solid at room temperature

• lower boiling points than ionic or giant molecular compounds

give 3 features of a giant covalent structure

• strong covenant bonds

• high melting and boiling points

• no charged particles, cannot conduct

give 3 examples of giant covalent structures

• diamond

• graphite

• silicon dioxide

allotropes

elements in different structural forms

eg diamond and graphite

give 3 reasons why diamond is hard

• each carbon atom forms 4 strong covalent bonds

• giant covalent structure

• bonds require a lot of energy to break

Give 3 properties of graphite

• each carbon atom has 3 covalent bonds, creating layers

• layers held by weak forces, they slide over each other

• one electron from each carbon atom is delocalised

why does graphite conduct electricity?

has delocalised electrons which carry electricity

give 4 properties of an alloy

• low melting point

• malleable

• distorted layers

• rust resistant

fullerenes

molecules of carbon shaped like hollow balls

nanotubes

tiny carbon cylinders

give 2 properties of a nanotube and some uses of them

• conduct electricity and heat

• not broken when stretched

• used in electronics and to strengthen materials

why are most metals malleable?

layers of atoms can slide over each other

what are the limitations of the simple model shown?

• no forces shown

• all particles are represented as spheres

• spheres are solid

why do ionic compounds only conduct electricity when molten?

when molten, ions are free to move so charge can easily flow