1.1 Formulae and equations Flashcards
What is oxidation number?
the number of electrons that need to be added or removed from an element to make it neutral (similar to ion charges)
Added = negative number Removed = positive number
what is electrostatic forces?
Forces between ions. Same charges repel, different charges attract.
What is intermolecular forces?
The forces that exist between molecules
What is intramolecular force?
Forces that hold atoms together within a molecule
How to determine the group and period of an element?
Use electron arrangement
E.g sodium 2,8,1
3 shells means it’s in PERIOD 3
1 electron in the last shell means it’s in GROUP 1
How to determine the charges of an element?
If an element ion is in group 1-4, the charge should be +1 to +4
If an element ion is in group 5, the charge should be -3
If an element ion is in group 6, the charge should be -2
If an element ion is in group 7, the charge should be -1
If an element ion is in group 8, the charge should be 0
General rules of oxidation number
Group 1 ➡️ always +1
Group 2 ➡️ always +2
Fluorine ➡️ always -1
Oxygen ➡️ always -2 ( however -1 in peroxide’s)
Hydrogen ➡️ usually +1 (however -1 in metal hydrides)
Chlorine ➡️ usually -1( however different in Oxygen and Fluorine)
What is the overall oxidation state in a neutral compound?
ALWAYS 0
What’s the oxidation number of ammonium chloride?
NH4Cl
H = +1 therefore H4 = 4x +1 = +4 Cl = -1
Note that the overall oxidation state in a neutral compound must be 0
So N has to be -3
What are negatively charged ions called?
Anions
What are positively charged ions called?
Cations
Why does some elements changed their name to have an ending of ide, ite and ate?
When the non-metals undergoing ionic bonding, they gain electrons
Ions ends in …ide : means that the ion is mono-atomic(by itself) e.g chlorine ➡️ chloride(Cl⁻),
Fluorine ➡️ fluoride(F⁻), Sulfur ➡️ Sulfide(S²⁻),
Nitrogen ➡️ Nitride(N³⁻)
Ions ends in …ite : means that the ion contains smallest number of oxygen. E.g Nitrite(NO₂⁻), Sulphite(SO₃²⁻)
Ions ends in …ate: means that the ion contains the largest number of oxygen. E.g Sulphate(SO₄²⁻), Nitrate(NO₃⁻)
Why do elements obtain a full outer shell?
To become stable
What is oxidation and reduction in terms of oxygen transfer?
Oxidation = gain of oxygen Reduction = loss of oxygen
E.g Fe₂O₃ + 3CO ➡️ 2Fe + 3CO₂
Reduction from Fe₂O₃ to 2Fe (loss of oxygen)
Oxidation from 3CO to 3CO₂ (gain of oxygen)
What is oxidation and reduction in terms of hydrogen transfer?
Oxidation = loss of hydrogen Reduction = gain of hydrogen
E.g CH₂CH₃OH ➡️ CH₃CHO
Oxidation due to loss of hydrogen
E.g CH₃CHO ➡️ CH₂CH₃OH
Reduction due to gain of hydrogen
What is oxidation and reduction in terms of electron transfer
Oxidation = loss of electrons Reduction = gain of electrons
E.g Cu²⁺ + Mg ➡️ Cu + Mg²⁺
Reduction from Cu²⁺ to Cu (gain of electrons)
Oxidation from Mg to Mg²⁺ (loss of electrons)
What is an ionic compound?
Ionic compounds arebonding between metals and non-metals and are made up of positive and negative ions, held up together by electrostatic forces.
What are the general rules of ionic equations?
Acid + Metal ➡️ Salt + H₂
Acid + Metal base ➡️ Salt + H₂O
Acid + Metal carbonate ➡️ Salt + CO₂ + H₂O
What’s the product of Magnesium + Hydrochloric acid?
and chemical equation
Magnesium + Hydrochloric acid ➡️ Magnesium chloride + hydrogen
2Mg + 2HCl ➡️ 2MgCl + H₂
What’s the product of Calcium hydroxide + Nitric acid?
and chemical equation
Calcium hydroxide + Nitric acid ➡️ Calcium nitrate + Water
Ca(OH)₂ + 2HNO₃ ➡️ Ca(NO₃)₂ + 2H₂O
What’s the product of Magnesium Carbonate + Sulfuric acid?
and chemical equation
Magnesium Carbonate + Sulfuric acid ➡️ Magnesium sulphate + Water + Carbon dioxide
MgCO₃ + H₂SO₄ ➡️ MgSO₄ + H₂O + CO₂
How to calculate the charges
of an ionic bonding compound
Work out the charges of each element first and switch places, charges at top right corner of the first element switches to the bottom right corner of the second element and vice versa. Same charges CANCEL each other.
E.g Sodium Sulphate
= Na⁺ + SO₄²⁻
+ = +1 on Na⁺ goes to the bottom right of SO₄
2- on SO₄²⁻ goes to the bottom right of Na
so overall = Na₂SO₄
E.g Beryllium Nitrate = Be²⁺ + NO₃⁻ 2+ on Be goes to the bottom right of NO₃ - on NO₃ goes to the bottom right of Be so overall = Be(NO₃)₂
