Periodic Table
Group I Elements
Why??
I
Li Reactivity increases down the
Melting Point Decreases group because the electrons are
Na Density Increases become further and further away
from the positive (and therefore
K Reactivity Increases attractive) nucleus. This makes it
very easy for these elements to lose
electrons.
Properties
Low Density - They are very light metals, and Lithium, Sodium and Potassium can even float on water
Softness - They are soft and can be cut with a knife
Silvery Appearance - Freshly cut, they have a shiny luster, but they tarnish quickly in air.
Group VII Elements
Why??
E
Reactivity decreases down the
Cl Density Increases group, because the shells become
Br further and further away from the
positive (and therefore attractive)
I Reactivity Decreases nucleus. This makes it very difficult
for these elements to gain electrons.
-
Properties
Chlorine is a pale, yellow-green gas at room temperature
Bromine is a red-brown liquid at room temperature
Iodine is a grey-black solid at room temperature
All halogens exist as diatomic atoms
Displacement Reactions
Halide salts (combinations of Group VII and Group I elements) are colourless
Bromine water is orange A more reactive element (e.g. Chlorine) can displace a less
reactive element (e.g Bromine).
Chlorine water is colourless Potassium Bromide reacts with Chlorine to create Bromine
Iodine water is brown and Potassium Chloride. This results in an orange solution.
However, Bromine cannot displace Chloride in a Potassium
Chloride salt, since Bromine is less reactive than Chlorine.
Ionic Equations
Step 1 - Rewrite ionic compounds in distributed form
Step 2 - Cancel spectator ions
Step 1 - Rewrite full equation
& Example: Cl2 + 2KBr —> 2KCl + Br2
-
Cl2 + 2K+ + 2Br- —> 2K+ + 2Cl + Br2
Cl2 + 2Br- —> 2Cl - + Br2
Ox. Agent Red. Agent
Group I Elements
Why??
I
Li Reactivity increases down the
Melting Point Decreases group because the electrons are
Na Density Increases become further and further away
from the positive (and therefore
K Reactivity Increases attractive) nucleus. This makes it
very easy for these elements to lose
electrons.
Properties
Low Density - They are very light metals, and Lithium, Sodium and Potassium can even float on water
Softness - They are soft and can be cut with a knife
Silvery Appearance - Freshly cut, they have a shiny luster, but they tarnish quickly in air.
Group VII Elements
Why??
E
Reactivity decreases down the
Cl Density Increases group, because the shells become
Br further and further away from the
positive (and therefore attractive)
I Reactivity Decreases nucleus. This makes it very difficult
for these elements to gain electrons.
-
Properties
Chlorine is a pale, yellow-green gas at room temperature
Bromine is a red-brown liquid at room temperature
Iodine is a grey-black solid at room temperature
All halogens exist as diatomic atoms
Displacement Reactions
Halide salts (combinations of Group VII and Group I elements) are colourless
Bromine water is orange A more reactive element (e.g. Chlorine) can displace a less
reactive element (e.g Bromine).
Chlorine water is colourless Potassium Bromide reacts with Chlorine to create Bromine
Iodine water is brown and Potassium Chloride. This results in an orange solution.
However, Bromine cannot displace Chloride in a Potassium
Chloride salt, since Bromine is less reactive than Chlorine.
Ionic Equations
Step 1 - Rewrite ionic compounds in distributed form
Step 2 - Cancel spectator ions
Step 1 - Rewrite full equation
& Example: Cl2 + 2KBr —> 2KCl + Br2
-
Cl2 + 2K+ + 2Br- —> 2K+ + 2Cl + Br2
Cl2 + 2Br- —> 2Cl - + Br2
Ox. Agent Red. Agent
