Chapter 8/12 - Reactivity Series and Periodic Table

Question 1

Reactivity series

Reduction and oxidation (redox)

Oxidation = addition of oxygen
Reduction = removal of oxygen
Oxidation 
Is
Loss of electrons
Reduction 
Is
Gaining

Answer 1

K:  : = metal + cold water > metal 
Na:      Hydroxide + hydrogen
Li:
Ca:
Mg; ; = metal +steam > metal oxide + hydrogen
Al;
C;
Zn;
Fe;
Sn;
H;
Cu, Ag,Au, Pt - dont react with water or steam

Question 2

Example of redox reaction

Mg(s) + CuO(s) > MgO + Cu(s)

Mg• + Cu(2+) O(2-) > Mg(2+) O(2-) + Cu•

Mg• - 2e > Mg(2+)
Cu(2+) + 2e > CuO

• = 0 
e = -1
\+ = +1

Answer 2

Displacement reactions

• when a more reactive metal displaces a less reactive metal

Mg + CuO > MgO + Cu
Mg switches with Cu as mg is more reactive

Question 3

Periodic Table

Group No. = electrons on outer shell
Period No. = Amount of shells
- Arranged in order if atomic number (# protons)
- # protons = # electrons = electronic structure
- Elements in the same group have similar electronic structure

Answer 3

Transition metals

• Tend to make 2+ Ions (Ag1+) but have multiple oxidation states
• Relatively unreactive/make colourful compounds when they do react
• Often used as catalysts

Noble gases: Unreactive as they have full outer shell, colourless, Gases (v.low M.P/B.P)
- Exist as atoms not molecules therefore only weak attraction between atoms

Question 4

Group 1 - Alkali metals

• Alkali metals react most easily as there is only 1 electron to lose
• Alkali metals become more reactive as you go down group: 1) Outer electron is further away
  from nucleus so less attraction (easier to lose)
  2) Electrons on the inner shell shield outer electrons from nuclear attraction
  Other aspects: Not dense (Li,K,Na) not dense than water/Soft (can cut with butter knife)/M.P decreases down the group

Answer 4

Alkali Metals With Water

React with water displacing Hydrogen to produce soluble metal hydroxide
2Am(s) + 2H2O(l) > 2AmOH + H2(g)

Lithium - fizzes around surface, leaves trail of LiOH which readily dissolves and gas produces
Sodium - As for Lithium but melts into a ball telling us it has a lower M.P
Potassium - Same as Na + Hot enough to ignite H2 which burns with a lilac flame

Question 5

Halogens

• Like all non metals except group 8 halogens react by gaining electrons
• Have 1 electron to gain - becomes less reactive as we go down the group

Answer 5

Why?

1) Outer shell is further away so there is a weaker attraction to electrons from nucleus
2) Greater shielding as more shells so weaker attraction from nucleus to the electrons
3) M.P/B.P increases as the molecules become larger and so more intermolecular forces