Periodic Table

Question 1

Describe the periodic table

Answer 1

The Periodic Table is arranged in increasing increasing proton numbers

Vertical columns are GROUPS (ROMAN NUMERALS)
Elements of the same group have the SAME number of VALENCE electrons
- They have similar chemical properties
- They form ions with the same charge
Going down the group There is an increase in metallic properties
- Size of atom increases,
- Valence electrons are further away from attractive force of nucleus
- Elements lose valence electrons more easily

Horizontal rows are PERIODS
Elements of the same period have the same number of electron shells
Elements become less metallic as they move from left to right across the Periodic Table
The ability of the element to lose electrons decreases across the period from left to right

Question 2

What are the physical properties of group I/ alkali metals

Answer 2

Alkali metals are:
- Soft and can be cut easily
- Low melting points <200°C
- Low densities, (Li, Na, K g=floats on water)

Question 3

What are the chemical properties of group I/alkali metals?

Answer 3

They are highly reactive; need to be stored in oil (not to expose to moisture in air)as they only have one valence electron, they lose their valence electron easily to achieve a fully filled electron shell

1. They react with cold water to form an alkali and hydrogen gas
   eg. 2K (s) + 2H2O (l) -> 2KOH (aq) + H2 (g)
   Observation:
   - Effervescence
   - Darts on surface of water
   - Burns with lilac flame
   - Melts into silvery ball
2. They are powerful reducing agents as they lose/give electrons readily
3. Form ionic compounds

Question 4

What are the properties of group I/alkali metals?

Answer 4

• Low mp & bp
• Low densities
• Reactivity increases down the group
  (As size of atoms increases, valence electrons further from nucleus, force of attraction weaker, easier to lose valence electron)
• React with water to form an alkali and hydrogen
• Powerful reducing agents
• Form ionic compounds

Question 5

What are the physical properties of group VII/ halogens?

Answer 5

Halogens are:
- Non-metals that exist as diatomic covalent molecules
- Have low mp & bp
- Are coloured

Fluorine- pale, yellow gas
Chlorine - greenish, yellow gas
Bromine - reddish brown liquid
Fluorine - black solid/purple gas/brown aqueous solution

Question 6

What are the chemical properties of group VII/ halogens

Answer 6

1. Reacts with most metals salts called halides
2. Undergo displacement reactions with halide solutions
   MORE reactive halogen will DISPLACE a less reactive halogen

eg. Cl² (aq) +2NaBr (aq) -> 2NaCl (aq) + Br² (aq)
Colourless solution turns reddish brown
eg. Cl2 (aq) + 2NaI (aq) -> 2NaCL (aq) + I2 (aq)
Colourless solution turns brown

3. Are powerful oxidising agents as they gain electrons readily

Question 7

What are the properties group VII/ halogens

Answer 7

• Exist as diatomic covalent molecules
• Low mp & bp
• Colour becomes darker down the group
• Reactivity decreases down the group
  (As size of molecules increases, intermolecular forces becomes stronger, more energy is needed to overcome forces of attraction of attraction)
• More reactive halogen displaces less reactive halogen
• Powerful oxidising agents

Question 8

What are the properties of group 0/ noble gases?

Answer 8

1. Monoatomic non-metals
2. Have low mp & bp
3. Unreactive/ inert, do not form ions or molecules
   Their atoms have fully filled valence electrons, do not need to form bonds with other atoms

Question 9

What are the noble gases and their uses?

Answer 9

Helium - Used for filling weather balloons
Neon - Used in making lights and advertising signs
Argon - Used to fill light bulbs or providing inert atmosphere during welding/making steel
Krypton - Used in flash bulbs for photography
Xenon - Used in vehicle headlamps and lasers

Question 10

What are the properties of transition metals

Answer 10

• High mp & bp
• High densities
• Form coloured compounds
• Have variable oxidation states
• Used as catalysts in industrial processes

Question 11

What are different transition metal coloured compounds?

Answer 11

Fe2+ compounds*
FeCl2 pale green
Fe(OH)2 dark green

Fe3+ compounds*
Fe2(SO4)3 yellow
Fe(OH)3 reddish-brown

Cu2+ compounds*
CuCl2, CuCO3 green
Cu(NO3)2, CuSO4, Cu(OH)2 blue

(Mn2+) MnSO4 pink
(Mn7+) KMnO4* purple (oxidising agent that turns colourless if reducing agent present, itself is reduced)

Question 12

What are the different transition metal catalysts?

Answer 12

Iron - Haber process
Nickel - Making margarine (hydrogenation of vegetable oil)
Platinum-rhodium - Catalytic converter
Titanium (III)/(VI) chloride, Polymerisation of alkenes
Manganese (IV) oxide - Decomposition of hydrogen peroxide, H2O2