Periodic Table - Grp I

Question 1

group I

• they are called _____
• react with ___ to form ______ solutions
• usually react to form _____ -> cant really be found by itself

Answer 1

• alkaline metals
• water, alkaline
• compounds

Question 2

physical properties of group I (7)

Answer 2

1. low mp/bp
2. low densities (Li, Na, K can float on water)
3. soft
4. shiny, silvery when freshly cut
5. good conductors of heat and electricity
6. malleable, ductile
7. all grp I elements form soluble oxides and hydroxides

Question 3

trends down grp I (2)

Answer 3

1. mp decreases

2. density generally increase – Li, Na, K less dense than water

Question 4

reason for mass of grp I

Answer 4

least number of proton, neutron compared to grp II, III, transition metals
more proton, more neutron, more mass

Question 5

reason for trends of grp I – physical properties (2)

Answer 5

1. mp:
   - size increase down grp
   - dist between the nuclei and the valence electron is further so the electrostatic forces of attraction between nuclei of metallic cations and delocalised electrons are weaker
   - less energy required to overcome the electrostatic forces
   - hence mp decrease down grp
2. soft:
   - electrostatic forces of attraction between grp I metallic cations and sea od delocalised electrons are weaker compared to other metals for other groups and are easily broken

Question 6

chemical properties of grp I (3)

Answer 6

1. most reactive metals
2. lose one electron, +ve ion, charge of +1
3. act as reducing agents, reducing effect increase done grp

Question 7

grp I reactions with water

• general observations and the reason for the difference in observations
• equations and observations of Li Na K

Answer 7

1. reacts vigorously and rapidly to form hydrogen gas and an alkaline solution
   - reactions for all elements are the same only diff is the speed of losing the electron (cos of size)

larger atom -> weaker attractions -> faster to lose electron

2Li (s) + 2 H₂O (l) –> 2 LiOH (aq) + H₂ (g)
Lithium reacts gently with water.
Effervescence of a colourless, odourless gas which extinguishes a lighted splint with a pop sound
The lithium metal darts around and sizzles on the water’s surface

Sodium reacts violently with water

Potassium reacts explosively with water

Question 8

grp I reactions with chlorine + equation Na

Answer 8

• react readily to form chlorides

2Na (s) + Cl₂ (g) –> 2 NaCl (s)

Question 9

reason for trend down grp I – chemical properties (1)

Answer 9

1. reactivity increases down grp I
   - size increases as number of electron shells increases
   - dist between the nucleus and valence electron increases
   - electronic forces of attraction between valence electron and nucleus weaker
   - valence electron to be lost more easily
   - therefore reactivity increases – changes occur faster, speed of reaction increase

Question 10

explain why grp I metals are stored under oil

Answer 10

Alkali metals are very reactive and react readily with oxygen in the air to form a layer of metal oxide. They are stored under oil to prevent this reaction from occurring.