structure and bonding

she acts like summer and she walks like rain

ionic bonding

between metals and non metals, one atom loses an electron and one gains one (e.g. NaCl), opposite charged ions attract each other and bond by electrostatic forces

ionic lattice

structure made up of regular pattern of ionic bonds

why do ionic compounds have high melting/boiling points?

electrostatic forces of attraction between the ions are strong so it takes a lot of energy to overcome them

why can ionic compounds conduct electricity when in liquid state but not solid state?

when in liquid state, the ions are free to move but in solid state, the ions are stuck :(

simple covalent bonding

between non metals, pair of electrons shared between atoms (e.g. CO2 which has a double bond)

why do simple covalent structures have low melting/boiling points?

there is not much energy needed to overcome the weak intermolecular forces between the molecules the actual covalent bonds are not broken)

why are simple covalent structures such bad conductors?

they don’t have an overall charge as they don’t contain any charged particles

giant covalent structures

many atoms joined by covalent bonds

metallic bonding

between metals, sea of dealocalised electrons and atoms arranged in regular pattern, sharing of delocalised electrons creates strong metallic bonds

why are metals good conductors?

delocalised electrons carry charge through the metal (good conductors of thermal energy because delocalised electrons transfer energy)

why do metals have high melting and boiling points?

because large amounts of energy are needed to overcome the strong metallic bonds

why are alloys harder and stronger than pure metals?

contain atoms of other elements, atoms have different sizes, so they distort the layers of atoms in the pure metal, this means that a greater force is required for the layers to slide over each other

why do giant covalent structures have high boiling/melting points?

large amounts of energy are needed to overcome the strong covalent bonds

why are giant covalent structures bad conductors?

have no free charged particles BUT graphite is an exception as it has delocalised electrons

converting from nm to cm

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polymers

large molecules joined by covalent bonds

why do polymers have high boiling/melting points?

a high amount of energy is needed to overcome the strong intermolecular forces