Unit 1 - Definitions Flashcards
Valency
The number of bonds an element needs, to have a full outer shell.
Ions
An ion is an atom or molecule with a net charge due to the loss or gain of one or more electrons.
What is an atom?
The smallest a substance can be and still stable.
Atomic number
Atomic number is the number of protons in the nucleus of an atom.
Mass number
The number of protons and neutrons in the nucleus of an atom.
Neutral atom
Protons and electrons are equal.
Positive charges and negative charges cancel out.
Defenition of Isotopes
An isotope is
2 or more atoms (of the same element) with the same atomic number but different mass numbers.
Definition of isotopes in terms of particles
2 or more atoms (of the same element) with the same number of protons but different numbers of neutrons.
Relative atomic mass
Relative atomic mass is the mass of an element relative to the proportion of each isotope.
Solutions and solubility
Solute - the substance that dissolves in the solvent.
Solvent - the liquid that dissolves the solvent
Solution - the substance made from the solute and solvent.
Saturated - when no more solute dissolves in the solvent.
What is a catalyst?
Catalysts are substances that speed up a reaction without being used up in reaction.
Definition of
Rate of reaction
The rate of a reaction is a measure of how quickly a reactant is used up, or a product is produced.
Why do atoms form bonds?
Atoms form bonds to achieve a full stable electron arrangement.
(Like a noble gas)
Covalent bond
A covalent bond is an electrostatic force of attraction between the positive nuclei and the shared electrons.
Ionic bonds
An ionic bond is an electrostatic force of attraction between positive and negative ions.
Molecule
A small number of non-metal atoms covalently bonded together.
Electrolysis
Electrolysis is the process of
Separating a compound into its elements using electric current.
Gram formula mass
gfm = the relative atomic mass for 1 mole of an atom.
The mass in grams of 1 mole of an element or compound.
Universal indicator
Universal indicator is used to tell if something is a acidic, alkali or neutral.
pH
pH is the number which indicates how acid or alkaline a substance is.
(pH means power of hydrogen)
What are acids?
Acids are solutions containing a greater concentration of hydrogen ions than hydroxide ions.
What are alkalis?
Alkalis are solutions containing a greater concentration of hydroxide ions than hydrogen ions.
An Alkali is a soluble base.
What are neutral solutions?
Neutral solutions contain an equal amount of hydrogen and hydroxide ions
What is a base?
A base is defined as anything that neutralises and acid.
How are acids made?
Acids are made when:
Soluble non-metal oxides form acids when dissolved in water.
How are alkalis made?
Alkalis are made when:
Soluble metal oxides form alkalis when dissolved in water.
What is pH dependent on?
pH is dependent on the concentration of hydrogen ions in a solution
What is a neutralisation reaction?
A neutralisation reaction is a reaction in which a base reacts with an acid to form water.
(A salt is also produced)
Titration
Titrations are used to calculate the concentration of an unknown solution by reacting it with a solution of known concentration, known as a standard solution.
Solute
Solute (substance) dissolves (in the solvent)
Solvent
Solvent (the liquid) dissolves the solute
Solution
The substance that is made from the solute and solvent
Solute + solvent
Saturated
No more solute can dissolve in the solvent
Covalent molecule
Have fixed - shapes, sizes and formulae (non-metals)
What are delocalised electrons?
Delocalised electrons are electrons that are free to move between the layers. This allows electricity and heat to be conducted.
What are charged particles called?
Ions
Monatomic
A substance which exists as single, unbonded atoms.
E.g. noble gases
Ions - metals and non-metals
Non metal form ions by GAINING electrons to form negative ions.
Metals form ions by LOSING outer electrons to form positive ions.
Ions - Charge and valency
The charge on the ion equals its valency.
Types of bonding
Covalent - non metals only
Ionic - metals and non metals only
Metallic - metals only
Number of methods to react/collect gases?
2 methods - they are interchangeable
Diagrams in jotter
3 common lab acids
Hydrochloric acid (HCl) Nitric acid (HNO3) Sulfuric acid (H2SO4)
Test for hydrogen gas
Burns with a popping sound. ?
Test for carbon dioxide
Carbon dioxide gas turns lime water cloudy.
Test for oxygen
Oxygen gas relights a glowing splint.
Examples of bases (4)
Neutralisation
- metal oxide
- metal hydroxide
- metal carbonate
- ammonia
Describe a diatomic molecule
A molecule made up of only 2 atoms (they can be the same atom or 2 different atoms)
Dissociation of water equation
H2O H+(aq) + OH- (aq)
Ions in acids and alkalis
Acids contain a higher concentration of H+ ions that OH- ions.
Alkalis contain a higher concentration of OH- ions that H+ ions.
Neutral substances contain equal concentrations of OH- and H+ ions.
Neutralisation equations
Metal oxide + acid —-> water + salt
Metal hydroxide + acid —-> water + salt
Metal carbonate + acid —-> water + salt + carbon dioxide
Spectator ions
A spectator ion is an ion which h is present in a reaction but is not involved. It is ‘spectating’.
Titration method
An indicator shows the end point.
A rough titre is done first to give a rough idea of quantities. It is NEVER used for calculations.
A white tile is used to make the colour change clearer.
Repeat until results are concordant (within 0.2cm³ of each other)
An average titre is calculated from the 2 concordant titres.
