Studied by 3 people
what is a chemical bond
an electrostatic force of attraction between positively and negatively charged species
what are the three types of chemical bonding
covalent bonds
ionic bonds
metallic bonds
what is a covalent bond
where electrons are shared by two positive nuclei
what is an ionic bond
a bond formed when positive and negative ions are attracted to each other
what is a metallic bond
a bond formed when metal atoms are packed closely together and are bonded to each other by delocalised, free-moving valence electrons
description of a covalent molecule/bond
negatively charged bonding electrons are attracted to the positively charged nuclei of both atoms
this attraction holds the atoms together strongly
force of attraction is as a result of sharing a pair of electrons
description of an ionic lattice
strong electrostatic attraction between ions
each ion is attracted to the neighbouring, oppositely charged ion
resulting in a three-dimensional array of positively and negatively charged ions
description of a metallic lattice
three dimensional arrangement of metal ions
surrounded by delocalised valence electrons
when does a covalent bond form
when a pair of electrons are shared between the two atoms (usually between two non-metals)
description of a covalent bond forming
as the atoms get closer, valence electrons from each atom are attracted to the protons from the neighbouring atoms
this attraction pulls the atoms close together and the electron from each atom are shared
what are lewis structures used to demonstrate
only valence electrons
what is the centre atom for lewis diagram
whichever atom is closest to the left hand side
exceptions of having an octet of electrons
H, Be and B
where will regions of high electron density be arranged
as far as possible from the each other
why are regions of high electron density arranged so far away
to minimise the repulsion between the regions of high electron density
what does the shape of the molecule depend on
the number of regions of electron density around the central atom
the number of atoms bonded to the central atom
description of tetrahedral shape
4 sets of electrons arranged as far apart as possible
what is the bond angle for tetrahedral
109
description of trigonal planar shape
3 sets of electrons arranged as far apart as possible
what is the bond angle for trigonal planar
120
description of linear shape
2 sets of electrons arranged as far apart as possible
what is the bond angle for linear
180
what are the steps to determine the shape of the molecule
draw lewis structure for molecule
count the sets of electron on the central atom
count the number of bonded atoms (bonding sets of electrons)
overall molecule shape table
Note
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