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