Bonding Flashcards
definition of ionic bonding
the strong electrostatic forces of attraction between oppositely charged ions to form the electron configuration of a noble gas
this occurs between metals and non metals
what do ions arrange themselves into
what is each ion in it attracted to
a giant ionic lattice
attracted to the oppositely charged electrons
what is one property of ionic compounds regarding mp/bp
they are solids at room temperature as they have very high melting and boiling points due to strong electrostatic forces of attraction within each oppositely charged ions in the giant ionic lattice. it takes a lot of energy to overcome the strong electrostatic forces of attraction
can ionic compounds conduct electricity?
they will not conduct electricity in a solid state as the ions are not free to move. they will conduct electricity when molten / aqueous
what are ionic compounds like density wise and why?
they are brittle
because they can easily shift layers, then the like ions (charges) will line up and repel
what 2 things increases the strength of ionic bonds ?
1) the greater ionic charge of the ions
2) the smaller the ionic radius
what is a covalent bond
a covalent bond is a shared pair of electrons between two non-metal atoms
how can a shared pair of electrons form a bond
the shared pair of electrons are attracted to the protons in the 2 nuclei , forming a covalent bond
what are atoms that are not part of covalent bonds called
lone pair of electrons
what is dative/coordinate bonding?
when an atom uses a lone pair of electron’s to form a covalent bond with an atom which has a vacant orbital
how do we represent a dative bond
an arrow
what must the atom donating the electrons have?
a lone pair of electrons (2 electrons not used in bonding)
what must the atom receiving the electrons in dative bonding must have ?
a vacant orbital
is a dative covalent bond the same as a normal covalent bond
they have the same…
yes
the same average bond enthalpy
(tells us the strength of the bond)
what is electronegativity
the ability/power of an atom to attract a pair of electrons in a covalent bond
what happens when the covalent bond consists of 2 atoms of the same element?
the shared pair of electrons are attracted to the nuclei equally
why are noble gases not included in the electronegativity scale?
because they are unreactive
what is electronegativity based on
what is the highest number for electronegativity
the pauling electronegativity scale
4
what 3 factors does electronegativity depend on?
1) the size of the positive charge in the nucleus, moving left to right the number of protons increases which increases the attraction between nucleus and pair of electrons in the covalent bond
2) the atomic radius, from left to right the atomic radius decreases which means the closer the shared pair of electrons will be to the nucleus
3) shielding of nucleus by electrons in the inner shells, they screen the electrons in the outer shell from the positive charge in the nucleus
what’s a dipole
a bond or molecule that has a difference in charge caused by a shift in electron density
how to we show if a bond is polar
delta
+ -
what is metallic bonding
strong electrostatic forces of attraction between positive metal ions and the sea of delocalised electrons
what factors affect the strength of metallic bond
1) the ionic charge on the metal (higher =stronger metallic bonds)
2) number of delocalised electrons
3) the atomic radius (smaller = stronger )
3 properties of metals
good conductors of electricity
high melting and boiling points
metals are malleable and ductile (layers of ions
what does covalent bonding lead to the formation of
the formation of either simple or giant molecules
name 3 types of intermolecular forces in order of strength
1) van der waals forces between molecules
2) permanent dipole-dipole forces between molecules
3) hydrogen bonding between molecules
what’s van der waals forces
electrons are constantly moving from place to place so charge can change distributed at any time
this means one side of the
molecule can suddenly become more negative than the other side if the electrons have moved closer to that side
(this is called a temporary dipole )
how will a temporary dipole affect the neighbouring atoms and charge spread
(van der walls forces)
a temporary dipole in one molecule induces a dipole in the neighbouring molecules as it repels the electrons to the other side (induced dipole)
now there is a force of attraction between the $+ $- called van der waal forced
what intermolecular force do all molecules have
van der waal force
what affects the size of van der waal forces? (2)
- size/mr of the molecule (bigger molecule=more van der waals forces between molecules)
- surface area contact
what is permanent dipole-dipole forces between molecules
it only occurs between molecules which are polar
(a polar bond is a difference in electronegativity between atoms
there is a attraction between the oppositely charged deltas on the neighbouring molecules
what is hydrogen bonding
this is very similar to permanent dipole-dipole bonding however this only occurs with polar molecules which have hydrogen directly bonded to nitrogen , oxygen and fluorine
this is because they are the most polar molecules
hydrogen and these elements have a huge difference in electronegativity and as a result pull the pair of electrons in the covalent bond very strongly towards themselves
this leaves hydrogen very delta positive
the lone pair of electrons in the neighbouring molecule containing nitrogen, oxygen and fluorine is then attracted to the hydrogen
