bonding, structure & properties of matter Flashcards
what is ionic bonding?
the electrostatic force between positively charged metal ions and negatively charged non metal ions
what happens in ionic bonding?
a metal ion transfers electrons to a non metal ion, so both have full outer shells
what is an ionic compound?
a giant structure of ions, which have an ionic lattice ( a regular structure )
why do ionic compounds have a high melting and boiling point?
because they have an ionic lattice which contains many strong ionic bonds where ions are held together by electrostatic forces, a large amount of energy is needed to overcome these electrostatic forces, leading to a high melting or boiling point. however, higher charged ions will have a stronger ionic bond and stronger electrostatic forces between the ions, so will require a high amount of energy.
what is covalent bonding?
when 2 atoms share (a pair of )electrons to get a full outer shell of electrons
what is metallic bonding?
the force of attraction between delocalised negative electrons and positive metal ions (includes 2 metals)
how does metallic bonding occur? - this card gives info, no need to answer
metal atoms in pure metals tend to lose outer electrons, and instead of these electrons being transferred to another atom (ionic bonding) these ions become delocalised and are free to move around the metal structure, as these atoms have lost these electrons, they become positive ions, and there is then an attraction between the negative delocalised electrons and the positive metal ions which holds the atoms together in a metallic bond, which is why metals like iron, copper and gold can exist as solid, cohesive structures.
why do simple molecular substances have a low melting and boiling point?
they are small molecules, and the intermolecular forces holding the molecules together are weak, so a small amount of energy is required to overcome these forces
what are properties of substances with giant covalent structures?
high mp and bp, because a lot of energy is required to overcome the strong bons holding the atoms together. they also can’t conduct electricity, as there are no charged particles and they do not contain any ions
what is an alloy?
a mixture of 2 substances where at least one 1 is a metal - not chemically combined
why are alloys hard?
pure metals contain atoms of the same size, therefore when atoms are arranged in layers in metals, these layers of atoms can easily slide over each other, however in an alloy, the substance will contain a mixture of different sized atoms, making it harder for these layers of atoms to slide over each other, requiring a greater pressure to cause them to slide.
what is graphene?
graphene is 1 layer of graphite
explain the structure of diamond
diamond has a giant covalent structure ( contains many atoms held together by covalent bonds ) and each carbon atom has 4 covalent bonds with 4 other carbon atoms, it can’t conduct electricity, there are no free electrons
explain the structure of graphite
graphite can conduct electricity as it has 1 delocalised electron for each atom of carbon. it is arranged in layers of electrons, on each carbon atom, 3 covalent bonds are formed with 3 other carbon atoms
