Group 1 Alkali Metals

Question 1

Why do they react similarly in water?

Answer 1

Family of elements called alkali metals

Question 2

What is the general equation for reaction with water?

Answer 2

Alkali metal + water -> alkali metal hydroxide + hydrogen

2M(s). +. 2H20(l) -> 2MOH(aq) + H2(g)

Question 3

Li reaction with water

Answer 3

Appearance
- dull dark grey outside
- shiny + silver when cut
Observations for reaction with water
- reaction slower than sodium
- bubbles of hydrogen gas
- fizzing, floating, moving around
- UI solution blue

Question 4

Na reaction with water

Answer 4

Appearance
-dull light grey
- shiny silver when cut
Observations 
- floats and moves around
- fizzes+ melts into a sphere
- bubbles of hydrogen gas
- white trail of sodium hydroxide produced, which dissolves in the water 
- UI solution turns blue

Question 5

K reaction with water

Answer 5

Appearance

• dull dark grey, but shiny inside
• tarnishes v quick

Observations:

• floats
• moves around quickly, fizzing + crackling
• reacts more strongly than sodium
• melts into shiny ball that dashes around the surface
• produces lilac flame as it reacts
• UI solution blue

Question 6

Trend of reactivity

Answer 6

Reactivity increases down the group
Reacts more vigorously as you go down the group,
- further an electron is from positive nucleus (ie if the element has a lot of shells, further down the group) the easier it can be lost in reactions BECAUSE SHIELDED FROM MORE POSITIVE NUCLEAR CHARGE BY INNER ELECTRON SHELLS
less attracted to nucleus -> easier to remove

Question 7

Equation for lithium reacting with oxygen

Answer 7

Lithium + oxygen -> lithium oxide

4Li (s) + O2 (g) -> 2Li2o (s)

Question 8

What are the word and chemical equations for the reaction that causes sodium to tarnish?

Answer 8

Sodium + oxygen -> sodium oxide

4Na (s) + O2 (g) -> 2Na2O (s)

Question 9

Equation for lithium reacting with water

Answer 9

Lithium + water -> lithium hydroxide + hydrogen

2Li (s) + 2H2o (l) -> 2LiOH (aq) + H2(g)

Question 10

Equation for reaction of sodium with water

Answer 10

2Na (s) + 2H2O (l) -> 2NaOH (aq)) + H2 (g)

Sodium + water -> sodium hydroxide + hydrogen

Question 11

Equation for reaction of potassium with water

Answer 11

Potassium + water -> potassium hydroxide + hydrogen

2k (s) + 2H2O (l) -> 2KOH (aq) + H2 (g)

Question 12

The trend of reactivity in group 1 metals with air

Answer 12

Lithium - red flame
Sodium - yellow/orange flame
Potassium - lilac coloured flame

Question 13

Trends in reactions with water (yes, repeat everything, but its worth it)

Answer 13

Lithium - bubbles of hydrogen gas
Sodium - bubbles of hydrogen gas
- melts into a shiny ball that dashes around the surface
Potassium - bubbles of hydrogen gas
- melts into a shiny ball that dashes around the surface
- burns with lilac coloured flame

Question 14

Predicted reaction of rubidium, caesium and francium with water

Answer 14

More vigorous

Question 15

Trend in reactivity in group 1 in terms of electronic configurations

Answer 15

• reactivity increases down the group
• each outer shell contains only one electron
• > when grp 1 metals react they will lose one outer electron to get full outer shell of electrons
• number of shells of electrons increases down the group
• means outer electron is further away from nucleus so there are weaker forces electrostatic forces of attraction
• requires less energy to overcome electrostatic forces of attraction between negatively charged electron and positive nucleus
• allows electron to be lost easily, making it more reactive down the group