Chemistry Flashcards
What is the symbol for sodium?
Including information
23
Na
11
11 protons
11 electrons
12 neutrons
What are elements?
Substances made up from one type of atom.
What’s a compound?
What is formed when two or more elements combine together.
What are the charges and masses of protons, neutrons and electrons?
Protons: +1 / mass 1
Neutron: 0 / mass 1
Electron: -1 / 0.001
What is the mass number and atomic number of an element?
Mass number: the total number of atoms, all protons, electrons and neutrons.
Atomic number: number of protons (and electrons)
Where are protons, neutrons and electrons found?
Protons and neutrons are in the centre of the nucleus.
Electrons are found in shells around the nucleus.
Info about the periodic table
The elements are arranged in columns called groups and rows called periods.
Atoms are represented by chemical symbols.
Group 1 are the alkali metals
Group 2 are the alkaline earth metals
Group 7 are the halogens
Group 0 are the noble gasses
The majority is made up of metals.
The further down the table / group, the more reactive the element is.
What is an electronic configuration / structure?
The amount of electrons on the shells of elements and the way it’s drawn, shells in order holding 2,8,8,2…
What is the electronic structure for argon?
40
Ar
18
2,8,8.
What do elements in the same group have in common?
They have the same number of electrons on their highest energy level e.g. Group 1 have one electron in their highest energy level / shell.
What is an ionic bond?
It is when a metal reacts with a non metal and ions are formed.
The elements want a full outer shell.
Metal atoms lose one or more electrons to form positively charged ions (because if they lose electrons then there will be more protons than electrons) and the non metals gain he electrons to form negatively charged ions (as there would be more electrons).
The oppositely charged ions attract each other strongly forming an ionic bond.
An example of an ionic bond is between lithium and fluorine as Li has one electron on it’s outer shell (which it wants to lose) and F has 7 electrons on its outer shell (and it needs one more for a full outer shell).
Atoms are lost or gained.
What’s a covalent bond?
It is when a non metal reacts with a non metal and molecules (group of bonded atoms) are formed.
The elements want a full outer shell.
An example of this is by a water molecule of H2O as oxygen has 6 electrons on it’s outer shell and hydrogen has 1 so two H atoms can share electrons with the oxygen atom to form H2O
Atoms are shared between the elements.
How would sodium and chlorine bond?
By an ionic bond.
How many atoms and elements are in: C2H5OH
3 elements
9 atoms
What happens to atoms in chemical reactions?
They rearrange themselves to form new substances.
Atoms are neither created nor destroyed so the number and type of atom stays the same before and after the reaction, meaning the mass of products = the mass of reactants.
This means we can write chemical equations to represent reactions. (Word equations give names, symbol equations show the numbers and types of atoms)
When symbol equations are written, they must be balanced / equal on both sides.
How do you balance an equation?
You can only change the large number in front of the symbol. Never change the small (subscript) numbers as this would change the formula of the substance.
Balance the equations:
H2 + Cl2 ~ HCl
Ca + O2 ~ CaO
Na + H2O ~ NaOH + H2
H2 + Cl2 ~ 2HCl
2Ca + O2 ~ 2CaO
2Na + 2H2O ~ 2NaOH + H2
What is the scientific name and chemical formula for limestone?
Calcium Carbonate
CaCO3
What happens when a carbonate reacts with an acid?
All carbonates produce a salt, water and CO2 gas when reacting with an acid.
What is another name for calcium hydroxide solution?
Limewater, used to test for CO2 (turning cloudy).
What happens to metal carbonates when heated strongly enough?
They decompose to the metal oxide and CO2.
What is the limestone reaction cycle?
Calcium carbonate
CaCO3
+ heat
Calcium oxide
CaO
+ little water
Calcium hydroxide
CaOH
+ more water and filter
Calcium hydroxide solution
Limewater
+ CO2
CaCO3
What are the uses of calcium hydroxide?
As it’s an alkali, it’s used to neutralise acids e.g. for soil within farming
Not very soluble but dissolves slightly to make limewater
It reacts with CO2 to form limestone
What is cement?
A substance made by mixing limestone with clay and heating it strongly which is ground up to make a fine powder.
What is mortar?
Cement mixed with sand and water to hold bricks and buildings together.
What’s concrete?
A material made by adding aggregate (small stones and crushed rocks) to cement, water and sand.
What are the pros and cons of limestone quarrying?
Pros:
More employment opportunities for locals
More customers and trade for local businesses
They are often restored
Can often mean that the roads will be improved too
Cons: Loss of habitats and wildlife More traffic Dust and noise Air and noise pollution
What is thermal decomposition?
The breaking down if a substance due to heat
What is the word and symbol equation for the thermal decomposition of limestone?
Calcium carbonate > heat > calcium oxide +
carbon dioxide
CaCO3 > heat > CaO + CO2
What is the order of reactivity of the elements from most to least: magnesium, copper, iron, potassium and carbon
Potassium Magnesium Carbon Iron Copper
Complete the displacement equation:
Copper oxide + carbon ~
Copper oxide + carbon ~ CO2 + copper
What’s an ore?
A rock containing enough metal to make it economically worthwhile to extract the metal.
What’s an alloy?
A mixture of metals (and sometimes non metals) e.g. Brass is a mixture of copper and zinc.
What is it called when oxygen is removed by a reaction?
Reduction
What is it called when oxygen is added by a reaction?
Oxidisation
Metals such as gold, which are very low in the reactivity series, don’t react with anything else so are found on their own or within rocks so can be separated physically.
However, most metals are found as compounds e.g. Iron oxide so they need to be separated by chemical reactions.
What is the method of separating the iron and oxygen?
Displacement
Metals can be extracted from compounds by displacement by using a more reactive element to ‘boot out’ the less reactive element e.g. Using carbon to separate iron and oxygen.
Reduction takes place as the carbon gains oxygen and iron is separated.
How is iron extracted?
In a blast furnace
Iron oxide is concentrated then is reduced in the blast furnace by using carbon.
It’s them separated but still has impurities, 96% iron, and the impurities make it hard and brittle.
Removing carbon and impurities makes pure iron but is too soft.
Give 2 uses and properties of aluminium
Uses:
Within aircrafts
Foil
Properties:
Low density
High in reactivity
Resistant to corrosion
Has to be extracted using electrolysis - expensive
Aluminium alloys are stronger and have more uses than pure aluminium
Give 2 uses and properties of titanium
Uses:
Turbine blades in a jet engine
Aircraft engines
Properties:
Strong
Resistant to corrosion
It can be reduced by carbon but the carbon reacts with the metal, making it brittle
What are the 5 ways copper can be extracted?
Smelting Displacement Electrolysis Phytomining Bioleaching
What’s smelting?
Heating the ore strongly in a furnace.
It produces impure copper which can be purified by electrolysis however this process requires huge amounts of heating and electricity.
What’s displacement?
When a more reactive element is used to ‘boot out’ the less reactive element e.g. Using carbon to separate iron and oxygen.
Reduction takes place as the carbon gains oxygen and iron is separated.
Displacement with copper occurs when solutions of copper compounds are reacted with a metal that is more reactive than copper, such as scrap iron, to displace the copper.
What’s electrolysis?
Using electricity to extract copper from a copper solution using electricity.
It’s done by a circuit and, in the copper sulphate solution, there are 2 carbon electrons; the positive - anode and the negative - cathode.
The electricity passing through the circuit causes the metal to separate from the solution and form on the cathode and gas is produced on the anode.
What’s phytomining?
A method of extracting copper done by plants absorbing copper compounds from the ground.
Then the plants, rich in copper, are burned to produce ash, high in copper, which is then extracted.