4.2 Flashcards
why are group 7 elements called halogens
they all form halide salts
why are fluorine & astatine often ignored
fluorine often behaves differently
astatine only exists as a radioactive isotope
are halogen molecules polar
no
summarize london forces
electron density continuously fluctuates due to movement
sometimes + & - charges don’t coincide
creating an instantaneous dipole
which induces a dipole on a nearby molecule
so there is a force of attraction between the molecules
what is group 7s trend in mp & bp
increases down the group
why do the halogens mp’s & bp’s increase down the group
more electrons
stronger instantanious dipole
stronger forces of attraction
require more energy to overcome
define electronegativity
the ability for an atom to attract a bonding pair of electrons in a covalent bond
why do group 7 have the highest electronegativity
big nuclear charge
short distance between nucleus and bonding pair
less shells therefor less shielding
which element has the highest electronegativity
fluorine
what is the trend in reactivity for the halogens
decrease down the group
why does reactivity decrease down group 7
electronegativity decreases down group (increased shielding, increased atomic radius)
where on the periodic table do the most vigorous reactions occur
bottom of group 1 & 2
top of group 7
what do ionic solids usually look like
white
how can you view the different colours of aqueous chlorine, iodine & bromine
add an organic solvent such as cyclohexane after the reaction as they will dissolve in organic layer and can be seen more easily
what colour is aqueous
-chlorine
-bromine
-iodine
chlorine - pale green
bromine - orange
iodine - purple
