N5 - Unit 1 Assessment Flashcards
What factors affect the rate of reaction?
Increasing concentration, decreasing particle size (or increasing surface area), increasing temperature and adding a catalyst
Describe the collision theory
Before a reaction can occur, the reactant particles must collide with enough energy to break the bonds in the reactants and allow new bonds to form.
What are catalysts?
Catalysts are substances that can speed up chemical reactions but can still be recovered in a chemically unchanged state at the end of the reaction. An example of a biological catalyst would be enzymes.
How can we follow the course of the reaction?
Reactions can be followed by measuring changes in concentration, mass and volume of the reactants and products. This data can be plotted as lines in graphs to show differences in the rate, quantity of product and the end-point of a reaction where conditions have been changed (for example, the quantity of the reactant, concentration, temperature, surface area and presence of catalyst)
How to do you calculate the average rate of reaction?
The change in mass can be calculated by using the change in mass or volume over/divided by the period of time. The final unit should be a combination of the units used in the question (for example, if ml were the unit of volume and seconds were the unit of time, the end unit would be ml/s)
How would you show that the average rate decreases over time?
By calculating the average rate at different points/parts of the graph/data.
What do you call a substance with only one kind of atom?
An element
How are elements in the periodic table arranged?
In order of increasing atomic number
What name is given to the columns in the periodic table?
Groups - the group number indicates the number of outer electrons of each element in the Group
What do elements within a Group share?
The same valency and similar chemical properties (because they have the same number of outer electrons)
How are compounds formed?
When elements react together
What is all matter made up of?
Very small particles called atoms
What features does a atom have?
A nucleus which contains protons and neutrons, and there are electrons which orbit the nucleus
What charges do protons, neutrons and electrons have?
Protons = 1+ Neutrons = 0 (neutral) Electrons = 1-
What amount of mass do protons, neutrons and electrons have?
Protons = Approximately 1 atomic mass unit Neutrons = Approximately one atomic mass units Electrons = Virtually no mass
How do find out the number of protons in an atom?
By looking at the atomic number
How do find out the number of electrons in an atom?
Equal to the number of protons (in a neutral atom ONLY)
How do find out the number of neutrons in an atom?
By subtracting the number of protons from the mass number - this means that the mass number is equal to the number of protons plus the number of neutrons
What are isotopes?
Isotopes are defined as atoms with same atomic number but different mass numbers, or as atoms with the same number of protons but different numbers of neutrons
What is Nuclide notation?
This is used to show the atomic number, mass number (and charge) of atoms (ions). The number of protons, neutrons and electrons can be determined from this.
( ) IONIC BONDING ONLY
How many isotopes do most elements have?
Most have 2 or more - Please note the word MOST
What is the average atomic mass?
This has been calculated for each element, it uses the mass and proportion of each isotope present
What is an ion?
When there is an imbalance in the number of the number of protons and electrons and the particle has an overall charge
How can atoms achieve a stable electron arrangement?
They can achieve this by forming bonds
What do covalent bonds form between?
Non-metals
What is a molecule?
A group of atoms held together held together by covalent bonds
How do covalent bonds form?
They form when 2 positive nuclei are held together by their common attraction for a shared pair of electrons
What are the 7 diatomic elements?
Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine and Iodine. These are all diatomic because of Covalent bonds
What can simple covalent molecules be described as?
Linear, Angular, Trigonal Pyramidal or Tetrahedral
Can more than one covalent bond be formed?
Yes - You can get double or triple covalent bonds
What can covalent substances form?
Discrete molecular (weak bonds) or Giant Covalent Network structures (strong bonds)
What features do covalent molecular substances have?
- Have strong covalent bonds within the molecules but only weak attractions between the molecules
- Have low melting and boiling points as only weak forces need to broken when changing state
- Do not conduct electricity because there are no charged particles that are free to move
- If they are insoluble in water they may dissolve in other solvents
What features do Covalent Network structures have?
- Have a network of strong covalent bonds within one giant structure
- Have very high melting and boiling points because the network of strong covalent bonds is not easily broken
- Do not dissolve
- Do not conduct electricity except Carbon Graphite
When are Ionic substances formed?
When metals combine with non-metals
When are ions formed?
When atoms lose or gain electrons to obtain the stable electron arrangement of a noble gas
What is the general rule of what sort of charge metals and non-metals have?
Metals have a positive charge because they LOSE electrons and non-metals have a negative charge because they GAIN electrons
What are ionic bonds?
They are the electrostatic attraction between positive and negative ions
What do ionic compounds form?
They form lattice structures (called ionic lattices) of oppositely charged ions with each positive ion surrounded by negative ions and each negative ion is surrounded by positive ions
Do ionic substances have high melting and boiling points?
Yes because strong ionic bonds must be broken in order to break up the lattice
Are ionic compounds soluble in water?
Yes because as they dissolve, the lattice structure breaks up allowing water molecules to surround the separated ions
Do ionic compounds conduct electricity?
Yes but ONLY when molten or in solution as the lattice structure breaks up allowing ions to be free to move
How can conduction in ionic compounds be described?
By the movement of ions towards oppositely charged electrodes
What is an electric current?
The flow of charged particles
What is electrolysis?
Flow of ions through solutions and molten compounds (electrolytes)
What does Electrolysis do to the electrolyte?
It chemically changes the electrolyte and could lead to breaking up of the compound
What happens during electrolysis?
Positive metal ions gain electrons at the negative electrode and negative non-metal ions lose electrons at the positive electrode
What is Metallic bonding?
It is the electrostatic force of attraction between positively charged ions and delocalised electrons
Do metallic elements conduct electricity?
Yes because they contain delocalised electrons which are free to move so can, therefore, conduct electricity
What do exothermic reactions do?
Release energy to the surroundings and the products have less energy than the reactants
What do endothermic reactions do?
Take in energy from the surroundings and the products have more energy than the reactants
How are compound names derived?
From the elements that they are formed of
What does the compound name ending “-ide” indicate?
That only the two elements mentioned in the name are present
What does the compound name ending “-ite” or “-ate” indicate?
That the two elements mentioned in the name are present AND oxygen
What are roman numerals used for?
To indicate the valency of an element (e.g. transition metals)
What does the chemical formula chemical molecular substances give?
Number of each type of atom present in a molecule
What does the formula of covalent network give?
The simplest ratio of each type of atom in the substance
Can chemical formulae be written for ionic compounds using valency rules and the data booklet?
Yes
What are ions containing more than one type of atom often referred to as?
Group ions
What does ionic formulae give?
The simplest ratio of each type of ion in the substance and can the show the charges of each ion.
i - Charges MUST be superscript and numbers of atoms/ions MUST be subscript
How can chemical reactions be described?
As word equations
What is formed when a solute is dissolved in a solvent?
A solution
What is the does the pH scale indicate?
The hydrogen ion concentration, it runs from below 0 to above 14 (most pH’s are measured from 1 to 14)
What pH’s do acids, alkalis and neutral solutions have?
Acids: Below 7
Neutral: 7
Alkali: Above 7
What concentrations of H⁺(aq) and OH⁻(aq) ions does a neutral solution have?
Equal concentrations
What concentrations of H⁺(aq) and OH⁻(aq) ions does an acidic solution have?
More H⁺(aq)
What concentrations of H⁺(aq) and OH⁻(aq) ions does an alkaline solution have?
More OH⁻(aq)
What happens when you dilute an acid or alkali?
Acid: Decrease H⁺(aq) concentration and increase pH towards 7
Alkali: Decrease OH⁻(aq) concentration and decrease pH towards 7
Do soluble non-metal oxides dissolve in water to form a acidic solution?
Yes
Do soluble metal oxides dissolve in water to form a alkali solution?
Yes
What do metal oxides, metal hydroxides, metal carbonates and ammonia solutions do?
Neutralise acids, they are called bases. Bases that dissolve in water form alkaline solutions.
What is a neutralisation reaction?
When a base reacts with a acid to from water and a salt is also formed.
How are the salts produced named?
This depends on the acid and base used, hydrochloric acid produces chlorides, sulfuric acid produces sulfates and nitric acid produces nitrates
What is a spectator ion?
A ion that remains unchanged in the reaction
How can we identify spectator ions?
We use reaction equations to identify spectator ions
In a acid-base titration, how is the concentration of the acid or base determined?
By accurately measuring the volumes used in neutralisation reaction, an indicator can be added to help show the end-point reaction
Can neutralisation reactions be used to prepare soluble salts?
Yes
Can you produce a soluble salt through titration?
Yes, if you repeat the experiment without the indicator (to produce a uncontaminated salt solution) and evaporate the solution to dryness
What can insoluble metal carbonates and insoluble metal oxides be used to produce?
Soluble salts, add excess base to the appropriate acid, filter then evaporate the mixture to dryness
Can the course be followed using a pH indicator?
Yes (if the base is insoluble then a indicator is not required)
What is a salt?
A compound in which the hydrogen ions of an acid have been replaced by metal or ammonium ions
