RX + PT Flashcards
Define oxidation (3)
- Addition of oxygen
- Loss of hydrogen
- Loss of electrons
Define reduction (3)
- Loss of oxygen
- Addition of hydrogen
- Gain of electrons
Define oxidation number
The oxidation state/charge of an element or ionic substance
Oxidation number of uncombined elements
0
Oxidation number of a monoatomic ion
The charge of the ion
Oxidation number of molecular ions
Sum of oxidation numbers is equal to overall charge
Oxidation number of a neutral compound
Overall charge is 0, sum of oxidation numbers is 0
Oxidation number of hydrogen
+1
Oxidation number of oxygen
-2
Oxidation number of halogens
-1
Oxidation number of group 1 metals
+1
Oxidation number of group 2 metals
+2
Oxidation number of oxygen in peroxides
-1
Oxidation number of hydrogen in metal hydrides (MHx)
-1
When are Roman numerals used?
For transition metals with variable oxidation numbers
Oxidation state of S block elements (Group 1 and 2)
- Lose electrons
- Oxidised
- Positive oxidation numbers
Oxidation state of P block elements
- Gain electrons
- Reduced
- Negative oxidation number
What is an oxidising agent?
- Gains electrons
- Reduced
- Increase in oxidation number
What is a reducing agent?
- Donates/loses electrons
- Oxidised
- Decrease in oxidation number
Define redox reaction
A reaction where reduction and oxidation occurs simultaneously
Define disproportionation reaction
A reaction in which an element in a single species is simultaneously oxidised and reduced
Trend in oxidation of metals
- Lose electrons
- Increase in oxidation number
- Oxidised
- Positive ions formed
Trend in oxidation of non metals
- Gain electrons
- Decrease in oxidation number
- Negative ions formed
Steps for ionic half equations and full ionic equations
- Write half equation for first element
- Balance all species excluding oxygen and hydrogen
- Balance oxygen by adding H20
- Balance hydrogen by adding H+ ions
- Balance charges using e- electrons
- Write half equation for second element
- Balance
- Ensure both equations have the same number of electrons
- Combine
- Cross off any common substances
What is the trend in ionisation energy going down groups 1 and 2?
Decrease in ionisation energy
1. More electrons going down the group
2. More quantum shells
3. Increased atomic radius
4. Distance between outermost electron and nucleus is greater
5. Weaker electrostatic attraction between nucleus and outermost electron
6. Less energy is required for the outermost electron to be removed
What is the reactivity trend going down groups 1 and 2?
Increase in reactivity
1. More electrons
2. More quantum shells
3. Larger atomic radius
4. Greater distance between outermost electron and nucleus
5. Weaker electrostatic attraction between outermost electron and nucleus
6. Less energy is required to remove the outermost electron
Reaction between group 2 metal with water
M(s) + 2H20(l) —> M(OH)2 (aq) + H2(g)
Group 2 metal + water —> Metal hydroxide + hydrogen
Reaction between group 2 metal and oxygen
2M(s) + O2(g) —> 2MO(s)
Group 2 metal + oxygen —> metal oxide
Reaction of group 2 metals (Sr and Ba) with excess oxygen
M(s) + O2(g) —> MO2
Reactions between group 2 metal and chlorine
M(s) + Cl2(g) —> MCl2 (s)
Group 2 metal + chlorine —> metal chloride
Reaction between group 1 metal and oxygen
4M + O2 —> 2M2O
Group 1 metal + oxygen —> metal oxide
Reaction between group 1 metal and excess oxygen
2M + O2 —> M2O2
Group 1 metal + excess oxygen —> metal peroxide
Reactions of group 1 metals and water
Group 1 metal + water —> metal hydroxide + H2
Reactions of group 1 metals and chlorine
Group 1 metal + chlorine —> metal chloride
Reaction between group 1/2 oxide and water
Group 1/2 oxide + water —> metal hydroxide
Group 1: M2O + H2O —> 2MOH
Group 2: MO + H2O —> M(OH)2