Topic 1-5 Flashcards
How did Melendeev arrange the elements?
- arranged the elements known at the time in a periodic table
- by using properties of these elements and their compounds
- also used this table to predict the existence and properties of some non discovered elements
How did Mendeleev predict era-aluminium would be a metal?
When gallium was discovered it’s properties closely fitted those he had predicted for Eka-aluminium
Describe the atomic structure
Has a nucleus that contains protons and neutrons surrounded by electrons in shells
Reason why atoms are neutral
Atoms contain the same number of protons and electrons so negative and positive charges cancel out
What’s is the mass number ?
Total number of protons and neutrons
What is the atomic number ?
Number of protons and electrons
Describe arrangement of elements
- Arranged in order of increasing atomic number arranged in periods
- Elements with similar properties are placed in the same vertical column called groups
What is an isotope ? And what Is the result of its existence?
- different atoms of an element with the same atomic number but different amount of neutrons
- results in relative atomic mass not being a whole number
What is the connection between increasing shells and placement in periodic table?
The more shells it has the more reactive the element is because inner electrons repel the outer electrons
What’s is formed when atoms of different elements combine?
A compound is formed by forming new chemical bonds
How are ionic bonds formed?
By transfer of electrons to produce cations and anions
Difference between a cation and anion
Cation
-metal atoms that lose electrons to form positively charged ions
Anion
-non metal atoms that gain electrons to form negatively charged ions
What is an exothermic reaction ?
A reaction which heat is released in forming bonds in the product is GREATER than energy needed to break bonds in the reactant
Collision theory
Increase temperature, surface area,concentration and add catalyst the frequency of successful collisions is greater
What happens when a metal reacts with a non metal to form a compound ?
- Electrons are transferred from metal atoms to non metal atoms
- this forms a positive charge for the metal ion and a negative charge for the non metal ion because it gains a negative charge
- oppositely charged ions attract each other strongly the new chemical bond formed is ionic
What charge is group 1,2,3,4,5,6,7,8
Group 1 1+ Group 2 2+ Group 3 3+ Group 4 -- Group 5 3- Group 6 2- Group 7 1- Group 8 0 - are inhert
What is an ion ?
A charged particle either negative or positive
What is the difference in compound endings ?
ide
No oxygen present
ate
Oxygen is present
Describe structure of ionic compounds as Lattice structures
- Ionic compounds as a lattice structure consists of regular arrangement of ions
- held together by strong electrostatic forces between oppositely charged ions
Name 5 compounds and their charge
Hydroxide OH- 1- Nitrate NO3 1- Oxide O2- 2- Carbonate CO3 2- Sulfate SO4 2-
Explain and describe properties of ionic substances
- *HIGH MELTING AND BOILING POINT this means they are solids at room temperature
- *ABILITY TO CONDUCT ELECTRICITY when molten or in aqueous solution
- *STRONG because energy is required to break the ionic bond and there is many of them in an ionic compound
Conditions for an ionic substance to conduct electricity
-substance must contain free to move charged particles (electrons)
**
Ionic compounds contain charged particles in a solid form ions are held in fixed position forming a lattice structure in which they can vibrate but are o free to move when molten or in aqueous solution
Under what conditions will a soluble conduct electricity
A soluble (e.g. NaCl) will dissolve in water and will conduct electricity under aqueous conditions
Under what conditions will a insoluble conduct electricity
An insoluble (e.g. MgO) does not dissolve at all in liquids , solids only conduct electricity when heated till molten
Suggest why magnesium oxide is used to line inside blast furnaces ?
MgO is a REFRACTORY material meaning it is RESISTANT TO HEAT
because it has high melting point because of the strong ionic bonds between magnesium (2+)and oxygen (2-)ions
Name the common substances soluble in water
(1. )Sodium potassium and sodium ammonium salts
(2. )All nitrates
(3. )common chlorides
(4. )common sulfates
(5. ) sodium carbonate , potassium carbonate, ammonium carbonate
(6. )sodium hydroxide, potassium hydroxide, ammonium hydroxide
List common types of insoluble substances in water
(1. ) silver chloride , lead chloride
(2. ) lead sulfate, barium sulfate , calcium sulfate
(3. ) rest of carbonates not listed in soluble
(4. ) most hydroxides not listed in soluble
How is a salt formed ?
Reacting acid with alkali
How are insoluble salts formed ?
Formed as precipitates by the reaction of suitable reagents in solution
E.g. Lead iodide forms a yellow precipitate
What is a Precipitate reaction ?
Two soluble substances produce an insoluble solid
Why is magnesium carbonate used
MgCO3 is hygroscopic which means it absorbs moisture , this property helps keep hands dry by providing more friction
How are precipitates separated ?
Precipitates can be separated from unreacted ions in solution by filtration washed on the filter paper then dried
Why is Barium to diagnose patients with intestine issues
Barium sulfate is given as a barium meal because it is opaque to x-rays and shows up as white on X-ray photographs
**Although barium salts are toxic it insolubility prevents it entering the blood*
What is spectroscopy?
To study light given off in flame test by samples of mineral water
Name a use of spectroscopy
To detect very small elements this lead to the discovery of rubidium and caesium
Name a 5 metal ions and their flame test colour
Sodium - yellow Potassium - lilac Calcium - red Copper - green Caesium - grey blue
What is the test for carbonate ions
Limewater turns cloudy when carbon dioxide bubbles through it
What is the test for sulphate ions
Mix dilute hydrochloric acid with Barium sulfate this forms a white precipitate if solution contains sulfate ions
Test for chloride ions
Mix dilute nitric acid and Silver chloride this forms a white precipitate if solution contains chlorine ions
What is a covalent bond?
A pair of electrons shared between two non metal atoms forming a double bond and to fill outer most shell
Name the simple molecular covalent substances
Hydrogen H2 Hydrogen chloride HCL Water H2O Meghan CH4 Oxygen O2 Carbon Dioxide CO2
Properties of simple molecular covalent
LOW MELTING AND LOW BOILING POINTS because of weak intermolecular forces between molecules are overcome
HAVE NO CHARGE This means they canning conduct electricity
USUALLY GAS OR LIQUID AT ROOM TEMPERATURE
Properties of giant molecular covalent
HIGH MELTING AND BOILING POINTS because each atom is joined or other atoms by strong covalent bonds and a lot of energy is required to break the bonds
Describe diamonds
Each carbon atom forms FOUR strong covalent bonds ( use of property cutting tools)
Does not conduct electricity because there are no free electrons or charged particles
Very
Describe graphite
Each carbon atom forms 3 COVALENT BONDS
SPARE ELECTRON CAN MOVE Around to CONDUCT ELECTRICITY
Carbon atoms are arranged in layers with weak forces of attracting between them which can slide over each other (lubricant)
What is immiscible and how are they separated
Liquids that do not completely mix with each other
SEPARATED USING SEPARATING FUNNEL
Miscible liquid and how they are separated
Liquids that completely mix with each other to make a solution
SEPARATED BY FRACTIONAL DISTILLATION because liquids have different BOILING POINTS
How fractional distillation works
Fraction with the HIGHEST BOILING POINT CONDENSES near bottom of column
Fraction with the LOWEST BOILING POINT reaches top of column and collected as a gas
What is chromatography used for
Separate and identify components or mixtures different solubilities of coloured compounds dissolve better in solvents
E.g. including colouring in food agents helps keep food safe
Analyse DNA samples to work out if suspects had been at crime scene
Transition metals facts
Located in central block of periodic table
HIGH MELTING POINTS
FORM COLOURED COMPOUNDS
SOME TOXIC but used in artist oil paints to give them colour
Alkali metals facts
Found in group 1 SOLIDS AT ROOM TEMP LOW MELTING POINTS SOFT CAN BE CUT WITH KNIFE ALL REACT WITH H20 ----> "metal" hydroxide and hydrogen gas All ions have 1+ charge
Alkali metals reaction in water
Lithium - floats on water and fizzes universal indicator green to purple
Sodium- fizzed around and forms molten ball on surface
Potassium - fizzed and heat ignited hydrogen a lilac flame is observed
Halogen facts
Form hydrogen halides when reacted with hydrogen
Elements in group 7
Fluorine - yellow gas AT ROOM TEMPERATURE and most reactive
Chlorine- yellow green gas AT ROOM TEMPERATURE and toxic
Bromine - brown liquid AT ROOM TEMPERATURE and toxic/volatile
Iodine - grey solid AT ROOM TEMPERATURE and sublimes from solid to gas does not form a liquid, gas a purple vapour
Displacement reaction
A more reactive substance displaces a less reactive substance from one of its compounds
Bromine and iodine displacements
Bromine
Sodium bromide + chlorine -> sodium chloride + bromine (aq)
Solution is colourless at first but turns orange brown when bromine formed
Iodine
Potassium iodide + chlorine ->’potassium chloride + iodine
Solution will turn brown black as iodine is formed
Nobel gases facts
Are in group 0
Very unreactive therefore are INERT
8 full outer shells meaning they are stable
DO NOT FORM IONS because they do not gain or lose electrons as they have complete shells
Colourless
Non flammable
Use of a Nobel gas
Helium - used in AIRSHIPS because it has a LOW DENSITY
Xenon/Argon- provided inert atmosphere in filament lamps to stop reactions with oxygen
Argon - used in fire extinguishers because it’s non flammable
Rate of reaction TEMPERATURE
Increase temperature
Reaction particle have more kinetic energy which increases the frequency of successful collisions
Decrease temperature
Reaction particles have less kinetic energy which decreases the frequency of successful collisions
Rate of reaction SURFACE AREA
increase
A larger surface area , increase rate of reaction as there is a larger area for acid or react WITH and increases frequency of successful collisions
Decrease
A smaller surface area will decrease frequency of successful collisions as there will be a smaller area for reactions to take place
Rate of reaction CONCENTRATION
Increase
A higher concentration will increase the frequency of successful collisions as there will be more reacting particles
Decrease
A lower concentration will decrease the frequency of successful collisions is there will be less reacting particles in the solution
Rate of reaction CATALYST
Adding
Adding a catalyst will increase the frequency of successful collisions as the reacting particles will react with less energy because catalyst lowers the activation energy
Removing
Removing catalyst will decrease the frequency of successful collisions as the reacting particles will need more energy to react
Temperature, surface area , catalyst graph analysis
Same quantity of reacting particles so same total product made at the end just happens at different rates (speed)
CONCENTRATION graph
Quantity of product changes
Higher concentration double (more) the product formed
Lower concentration half (less) of the product formed
Examples of exo and endo
Exo
Rusting
Combustion
Respiration
Endo
Photosynthesis
Dissolving ammonium nitrate in water
Measuring chemical change endo ammonium nitrate in water!! The CUP 😉
Thermometer
Lid
Cotton wool - insulate reaction to reduce heat being lost to environment
Polystyrene cup
Catalytic converters before and after
Before
Combustion of petrol produced toxic carbon monoxide and and burnt hydrocarbons that were released into the atmosphere
After
The carbon monoxide and hydrocarbons combined with oxygen from the air to form CO2 and water vapour
Catalytic converters now
Have a high surface area to increase the rate of reaction of carbon monoxide and hydrocarbons from exhaust gases with oxygen from the air to produce carbon dioxide is and water vapour work best at high temperatures as reactions are quicker
When engine is first started ….
Catalytic converter is cool so no reactions are taking place because rates of reaction is slow
