group 7- the halogens Flashcards
(24 cards)
how many electrons do group 7 elements have on their outer energy level/shell?
7 electrons
what happens if we take 2 atoms of a group 7 element and let react?
group 7 elements form molecules with 2 atoms joined by a covalent bond
what is covalent bonding?
the sharing of 2 electrons in order to achieve a full outer energy level
a fluorine molecule consists of 2 atoms, how can we represent the molecule?
F—F
how do the melting and boiling points of group 7 elements change as we move down the group?
the mp and bp increase as we move down the group
what does the melting and boiling point tell us about an element?
their physical state
a gas, a liquid or a solid at room temperature
around what temperature is room temperature?
20°C
the boiling point of fluorine is -188
the boiling point of chlorine is -29
what does this tell us about their physical state at room temperature?
they are both gases at room temperature because they’re boiling points are lower than 20°C
when an elements both boiling point and melting point is lower than 20°C
what is their physical state at room temperature?
a gas
when an elements melting point is lower than 20°C but it’s boiling point is higher than 20°C
what is the elements physical state at room temp?
liquid
when an elements both melting point and boiling point is higher than 20°C, what is their physical state at room temperature?
a solid
what does F—F or C—C represent?
a covalent bond
what is covalent bonding for?
atoms in an element aiming to achieve a full outer energy level by sharing electrons
when group 7 elements react with other NON-metals, what occurs
covalent compounds
represent the symbol for a covalent compound of Hydrogen and Chlorinde
H—Cl
what do group 7 elements form when reacting with
other non metals
metals
Covalent compounds
halogen + non-metal=covalent bonding
non metals + non metals= covalent bonds metals + non-metals= ionic bonds extra info : metals+metals= metallic bonding
when any group 7 elements react with a metal, how many electrons are gained and what ion is produced?
how do we write these
(use e.g)
gains 1 electron
an ion of 1- is produced
Flouride = F^-
Chloride=Cl^-
describe the reactivity series of the halogens
the elements get less reactive as we move down group 7
this is because
it gets harder to gain 1 electron as we move down the group
why is it harder gaining an electron moving down group 7?
-the great distance between the negative electron and the positive nucleus because of shells
-shielding of internal electrons
both these factors reduce the attraction of the electron on the outer energy level and the positive nucleus meaning there is less reaction
in displacement reactions of halogens, what is being displaced from what?
a more reactive halogen can displace a less reactive halogen from an aqueous solution of its own salt
what does an aqueous solution mean?
dissolved in water
in a displacement reaction, how would
sodium bromide+fluorine be displaced?
sodium fluorine + bromine
bromine is less reactive than fluorine. Fluorine displaces it
what is the displacement reaction of
potassium iodide+chlorine
potassium chlorine + iodine
chlorine is much more reactive than iodine.Chlorine displaces iodine
what happens to lithium chloride + bromine in a displacement reaction?
no reaction
chlorine is already more reactive than bromine as it’s higher up in group 7.no displacement is taken place.
