ALL PAPER 1 CHEMISTRY CONTENT
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62 Terms
What is an atom?
The smallest part of an element that can exist
What is the charge and relative mass of a proton?
Charge = +1, Relative mass = 1
What is the charge and relative mass of a neutron?
Charge = 0, Relative mass = 1
What is the charge and relative mass of an electron?
Charge = -1, Relative mass ≈ 0
What is the atomic number?
The number of protons in an atom (also equals electrons in a neutral atom)
What is the mass number?
The total number of protons and neutrons
How did Mendeleev arrange the periodic table?
By increasing atomic mass, but left gaps for undiscovered elements and grouped by properties
Why do elements in the same group have similar properties?
They have the same number of electrons in their outer shell
What are the properties of group 1 metals?
Very reactive, soft, low density, reactivity increases down the group
What happens when lithium reacts with water?
Fizzes and produces hydrogen gas and lithium hydroxide
What are the properties of group 7 elements (halogens)?
Reactive non-metals, coloured vapours, reactivity decreases down the group
What happens in displacement reactions of halogens?
A more reactive halogen displaces a less reactive halogen from a solution of its salt
What is an ionic bond?
The electrostatic attraction between oppositely charged ions (metal and non-metal)
What is a covalent bond?
A shared pair of electrons between two non-metal atoms
Why do ionic compounds have high melting points?
Strong electrostatic forces between ions require lots of energy to break
What are the properties of small covalent molecules?
Low melting/boiling points
weak intermolecular forces
don’t conduct electricity
What are the properties of giant covalent structures?
Very high melting points
hard
don’t conduct electricity (except graphite)
Why does graphite conduct electricity?
Each carbon bonds to 3 others, leaving one delocalised electron free to move
What is a metal alloy?
A mixture of a metal with other elements to improve strength
Why are alloys harder than pure metals?
Different sized atoms distort layers, making it harder for them to slide
How do you calculate relative formula mass (Mr)?
Add the relative atomic masses (Ar) of all atoms in the formula
What is the equation linking moles, mass and Mr?
Moles = mass / Mr
What is the limiting reactant?
The reactant that is completely used up in a reaction, limiting the amount of product made
What is concentration?
The amount of solute dissolved in a certain volume of solution
How do you calculate concentration?
Concentration = mass of solute / volume of solution
What is the pH scale?
A scale from 0–14 measuring how acidic or alkaline a solution is (7 is neutral)
What is the ionic equation for neutralisation?
H⁺ + OH⁻ → H₂O
What are the products of acid + metal?
Salt + hydrogen gas
What are the products of acid + base/alkali?
Salt + water
What are the products of acid + carbonate?
Salt + water + carbon dioxide
Required practical: how do you make a pure, dry salt from an acid and insoluble base?
React excess base with warm acid, filter to remove unreacted base, evaporate the solution to crystallise the salt
What is electrolysis?
Using electricity to split an ionic compound when molten or dissolved
Why must the ionic compound be molten or in solution for electrolysis?
So the ions are free to move and carry charge
What forms at the anode and cathode in electrolysis of molten compounds?
Positive metal ions go to the cathode (gain electrons),
negative non-metal ions go to the anode (lose electrons)
What is the half equation for sodium at the cathode?
Na⁺ + e⁻ → Na
What is the half equation for chlorine at the anode?
2Cl⁻ → Cl₂ + 2e⁻
What is the half equation for hydrogen at the cathode (aqueous solutions)?
2H⁺ + 2e⁻ → H₂
What is the half equation for oxygen at the anode (aqueous solutions)?
4OH⁻ → O₂ + 2H₂O + 4e⁻
In electrolysis of copper sulfate, what forms at the electrodes?
Copper at the cathode, oxygen at the anode
How do you predict the products of electrolysis in solution?
At cathode: least reactive metal or hydrogen forms. At anode: halide forms if present, otherwise oxygen
Required practical: what are the observations during electrolysis of copper chloride solution?
Reddish-brown copper forms at the cathode, bubbles of chlorine gas at the anode
What is oxidation and reduction in terms of electrons?
Oxidation = loss of electrons, Reduction = gain of electrons (OIL RIG)
What is a redox reaction?
A reaction where both reduction and oxidation occur
What are the rules for naming salts?
Metal/alkali provides first part of name, acid provides second part (e.g. hydrochloric acid + sodium hydroxide = sodium chloride)