bonding!! Flashcards
to understand how atomic, ionic & metallic bonding works
what is an ionic bond?
electrostatic attraction, oppositely charged ions
a strong, electrostatic force of attraction between oppositely charged ions
what must you show in dot and cross diagrams?
- outer shell electrons
- charges of each ion in brackets
what type of structure do ionic compounds have?
they have a giant lattice structure
how are lattice structures arranged?
they arranged in an ordered and repeating fashion
why do ionic cpds have high mp. and bp.?
the strong electrostatic forces of attraction need lots of energy to overcome them
why are ionic cpds good conductors of electricity?
(in molten or solution state)
the ions are in the solution or molten state are mobile and therefore able to carry charges
why are ionic compounds poor conductors of electricity in solid state??
the ions are at a fixed position in the lattice and therefore unable to carry a charge
how is a covalent bond formed?
it is formed when a pair of electrons is shared between two atoms
how many electrons is one covalent bond?
a pair of electrons
what is metallic bonding?
electrostatic attraction btw,. giant metal lattice… in a sea of ………
it is the electrostatic attraction btw. the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons.
what does malleability mean?
it means a metal can be hammered into shape
what does ductile mean?
it means a metal can be drawn/pulled into wires
how do the positive ions in a metal move when a force is applied?
they positive ions slide over each other
what is an alloy?
a mixture of metals eg. brass
why do metals have high melting points and boiling points?
strong electrostatic forces of attraction btw., …. need lots of energy
there are strong electrostatic forces of attraction between the positive metal ions and the negative delocalised electrons within the metal lattice structure that need lots of energy to be broken
why are metals good conductors of electricity?
DELOCALISED ELECTRONS FREE
the delocalised electrons are free to move and carry a charge through the whole structure
why are metals malleable?
atoms arranged in layers, sliding over
this is bc the atoms are arranged in layers which can slide over each when force is applied
describe the structure of graphite
(carbon)
carbon atom in graphite is bonded to three others forming layers of hexagons
(leaving one free electron per carbon atom which becomes delocalised)
what are allotropes?
different atomic or molecular arrangements of the same element in the same physical state
describe the structure of diamond?
In diamond, each carbon atom bonds with four other carbons, forming a tetrahedron
All the covalent bonds are identical, very strong and there are no intermolecular forces
describe the structure of silicon (iv) oxide
Each oxygen atom forms covalent bonds with 2 silicon atoms and each silicon atom in turn forms covalent bonds with 4 oxygen atoms
A tetrahedron is formed with one silicon atom and four oxygen atoms, similar to diamond
what type of compound in SiO
s a macromolecular compound which occurs naturally as sand and quartz
