S1 Chemistry Notes Flashcards
What did J.J. Thompson suggest about the atom?
Thompson suggested the atom consisted of a positively charged sphere with negatively charged electrons dotted throughout
What did Ernest Rutherford challenge this with?
Rutherford suggested that atoms have a (positive nucleus), around which, (electrons) (orbit in shells)
What experiment did Rutherford use to prove this? How did he do it?
(The gold foil experiment), wherein, he fired a beam of (alpha particles) at a (thin layer of gold foil). Some (particles) were (deflected) proving atoms have (dense nuclei)
What subatomic particle did James Chadwick discover?
The (Neutron)
What are the charges and masses of each subatomic particle?
M C
p = 1 +1
n = 1 0
e = 1/1840 -1
What is the maximum amount of electrons that the innermost shell of an atom can hold?
(2)
What is the maximum amount of electrons the outer shells of an atom can hold?
(8)
Define “ion”
An ion is (a charged particle) formed when (an atom) (loses or gains electrons) to achieve a (noble gas structure) / (full outer shell)
Define “isotope”
An (atom) with the (same) number of (protons and electrons) but a (different) (atomic mass) due to a different number of (neutrons) in the (nucleus)
What is the equation for calculating relative atomic mass (RAM)?
(Mass no. 1 * amount 1) + (mass no. 2 * amount 2)
———————————————————————
Total amount
What is “ionic bonding”?
(Ionic bonding) occurs in (compounds) containing a (metal atom) and a (non-metal atom), usually a group 1 or 2 element with a group 6 or 7 element. During bonding (electrons) are transferred from the (metal) to the (non-metal). This creates new compounds called salts
Or
An ionic bond is the electrostatic attraction between two oppositely charged ions
What is the name given to metal ions? (Positive)
(Cations)
What is the name given to non-metal ions? (Negative)
(Anions)
What are the physical properties of ionic compounds? Give a brief explanation for each (3)
• High melting and boiling points:
The bonds within the ions are extremely strong so take a substantial amount of energy to break the strong ionic bonds
• Soluble in water:
Ionic solids are dipolar which is why most ionic compounds are soluble in water. Dissolved ionic compounds form aqueous solutions
• Good conductors of heat and electricity when molten or dissolved:
if an (ionic compound) is dissolved or melted into a soft solid (molten) the ions are free to move and carry charge. When dissolved, ionic compounds such as sodium chloride can cause aqueous solutions to boil faster
How are molecules arranged in an ionic compound?
In a Giant ionic lattice, where the electrostatic forces of attraction hold the ions in a regular arrangement in rows where on every side of each ion there is an oppositely charged ion
Define “covalent bond”
A covalent bond is a shared pair of electrons between two or more non-metal atoms
Define “lone pair”
An (electron pair) in a (covalent bond) that is not (shared)
What is a diatomic element?
A (diatomic element) is a (non-metal element) that can (only exist by itself) if there (are two atoms) of it (covalently bonded)
How many electron pairs can exist in a covalent bond?
1, 2, or 3
(Single, double and triple covalent)
What are the types of covalent bond structure?
Simple molecular covalent
And
Giant colvalent lattice
How can the electronic structure of atoms and ions be drawn?
(Dot and Cross diagrams)
What other way can covalent compounds be drawn?
Structural formulae
This is where the symbol is connected by a line, relative to the number of covalent bonds in the compound, to the symbols of the other elements in the compound
E.g. O==O (double covalent)
Cl—Cl (single covalent)
Etc.
What is an allotrope? (3)
Allotropes are
- different forms
- of the same element
- in the same physical state
What are 3 allotropes of carbon?
(Diamond)
(Graphite)
(Graphene)
What sections does the modern Periodic table have that Mendeleev’s did not?
Lanthanides and Actinides (f block)
Noble gases group 8/0
+ a distinct transition metals section
What is the difference in terms of numbers of elements in the old and new periodic tables?
Medeleev’s = 63 elements
Modern = 118 elements
Was Medeleev’s periodic table full?
No,
Mendeleev left gaps in his table for newly discovered elements
What specific group of elements did Mendeleev’s table not include? Why?
Noble gases
They were very difficult to discover due to their non-reactivity
What specific difference is there in the modern and old sorting systems in the periodic table?
The modern system uses atomic number to order elements
Mendeleev’s system ordered elements in terms of atomic mass
What are the observations for a reaction between Lithium and water ? (5)
- lithium floats and spins on the water surface
- Effervescence/fizzing
- Lithium disappears at the end of the reaction
- Heat is produced (seen through steam)
- Colourless solution formed
What are the observations for a reaction between Sodium and water? (6/7)
- Sodium melts into a tiny ball
- Sodium floats and spins on water surface (more vigorously than lithium reaction)
- Effervescence/fizzing
- Heat released (seen through steam)
- Disappears at the end
- Colourless solution formed
+7. Chance to ignite with an orange flame (depends on volume of metal)
What are the observations for a reaction between Potassium and water? (8)
- Lilac flame produced
- Potassium melts into a tiny ball
- Potassium floats and spins on the surface of the water (most vigorously out of the three covered)
- Effervescence/fizzing
- Heat released (seen through steam)
- Potassium disappears quickly
- Colourless solution produced
- Crackles at the end/ chance to produce a small explosion
Give an example of an ionic equation (for Sodium)
Na —> Na+ + e-
Why does reactivity increase as you move down group 1?
As you move down group one, the elements have more shells which guard the positively charged nucleus. This causes the strength of the electrostatic attraction between the electrons in the outer shell and the positively charged nucleus to weaken, therefore the element loses the outer shell electron more easily and thus reacts faster.
Describe structure and bonding in Diamond
- Each carbon atom makes 4 strong covalent bonds
- Tetrahedral structure
Describe the structure and bonding in Graphite
- Each Carbon atom makes 3 strong covalent bonds
- Hexagonal layers
- between the layers are Weak Van der Waals forces
Describe the structure and bonding in Graphene
- One atom thick layer
- Each Carbon makes 3 strong covalent bonds
- Hexagonal layer
Explain the properties of Diamond
- No electrical conductivity as all electrons are involved in covalent bonds
- High M.P. and B.P. as it has many strong covalent bonds which require a substantial amount of energy to break
- Very strong as it has many strong covalent bonds which require a substantial amount of force to break
Explain the properties of Graphite (5)
- Electrical Conductivity is high as there is one delocalised electron per every covalent bond
- M.P and B.P high as they have many strong covalent bonds which require a substantial amount of energy to break
- Strong as they have many strong covalent bonds which require a substantial amount of force to break
- brittle as layers have Weak Van der Waals which require little force/energy to break
- insoluble in water as covalent bonds are too strong to break
What is metallic bonding? When does it occur?
Metallic bonding it the (electrostatic attraction) between (positive) (metal ions) and a (sea) of (delocalised electrons) and occurs in all (pure/ raw metals)
What is the knock-on effect of metals having delocalised electrons in their structure?
Metals can conduct electricity
What is the structure of metallic compounds?
(Giant metallic lattice)
What is an alloy? (3)
- mixture of elements
- at least one of which is a metal
- resulting mixture has metallic properties
How do alloys differ from pure metals?
They are (stronger) as the (metal cations) are (different sizes) making it (more difficult) to (separate) the (layers)
Why is pure gold not used in jewellery?
It is (too soft)
How do you calculate gold purity in an alloy?
Number of carats
———————— x 100 = % of gold in alloy
24
What size are nanoparticles?
Between (1 and 100nm)
What size are atoms
About (0.1nm)
Or
1 x 10-10m
How do nanoparticles differ from their respective bulk materials?
They have a high SA/V ratio
All elements have chemical symbols, this is usually the first letter of the name, though some use their Latin names.
Give three examples of elements like this.
Any 3 from:
Lead (Pb);
Potassium (K);
Tin (Sn);
Iron (Fe);
Copper (Cu);
Mercury (Hg);
Antimony (Sb); or
Sodium (Na)
Silver (Ag)
Gold (Au)
What do subscript numbers in chemical formulae represent?
(Number of atoms) of a (particular element) in a (compound)
What do large numbers represent in chemical formulae?
They are used to (balance) the (number of atoms) in (equations)
What is meant by the term “diatomic”?
An (element) that can only exist (by itself) when (covalently bonded) to (another atom) of the (same element)
What are the steps to balancing equations?
- Write word equation
- Write symbol equation
- Look out for diatomic elements
- Balance charge (in compounds)
- Balance atoms (large number in front of molecule)
What colour is chlorine water?
Colourless
What colour is bromine water?
Orange
What is the colour of iodine solution?
Dark brown
Can halogens displace each other?
Yes, when one is more reactive
How is the reactivity of halogens ordered?
Ascending order:
F
Cl
Br
I
At ^
What colour are the halogens?
Fluorine = pale yellow
Chlorine = green/yellow
Bromine = red/brown
Iodine = blue/black
Astatine = black
What is oxidation?
The loss of electrons from an ion in a reaction
What is reduction?
The gain of electrons by an ion in a reaction
Define halide
The name of a halogen when it has reacted with another substance and gained a full outer electron shell.
Define hydrogen halide
A compound formed from the reaction between hydrogen and a halogen.
Define metal halide
A compound formed from the reaction between a metal and a halogen.
Define volatile
A substance that evaporates or produces vapour at relatively low temperatures.
Define diatomic
Molecules that exist as two atoms covalently
bonded together.
Define displacement
The reaction when a more reactive element reacts with a compound containing a less reactive element.
What is the test for chlorine gas?
• Use damp universal indicator paper
• If chlorine is present it will
• turn the paper red
• And then bleach the paper to white
Why are the noble gases not referred to as group 8 and what is their actual name?
Helium has 2 electrons in its outer shell rather than 8
Therefore it is referred to as group 0
Why are noble gases chemically inert?
They don’t need to gain, lose or share electrons to become stable
How can you describe the physical properties of noble gases?
- Odourless, colourless gases
- Low boiling and melting points
- No electrical conductivity
Can noble gases be diatomic molecules?
No
They have a full outer shell and do not need to share electrons
What are the general properties of transition metals? (5)
- high melting points (except mercury)
- high density
- low reactivity with water (some react to form oxides and hydrogen with steam| others like copper don’t react with steam)
- react to form ions of different charges (e.g. Iron can form Fe2+ and Fe3+ ions.
- form coloured compounds (e.g. Copper (II) carbonate is green)
What colour is copper oxide?
Black
What colour is copper carbonate?
Green
What colour is copper sulfate?
Blue
What is the pH scale a measure of? In what order is this shown?
Concentration of H+ ions
0 is highest concentration, 14 is lowest
(Acid) (Alkali - releases OH- ions instead)
Name each indicator and their colour in acids, alkalis and neutral solutions
- Red Litmus : red in acid. Blue in alkali solutions. Red in neutral solutions
- blue litmus : red in acid. Blue in alkali solutions. Blue in neutral solutions
- phenolphthalein : colourless in acid. pink in alkali solutions. colourless in neutral solutions
- methyl orange : red in acid. yellow in alkali solutions. orange in neutral solutions
- universal indicator : red/orange/yellow in acid. Blue/purple in alkali solutions. green in neutral solutions
What is added to solutions to remove indicators?
Charcoal (then filter)
Name three strong acids and their formulae
Sulphuric acid - H2SO4
Hydrochloric - HCl
Nitric - HNO3
Name two weak acids and their formulae
Ethanoic acid - CH3COOH OR C2H4O2
Carbonic acid - H2CO3
Give two ionic equations for neutralisation. Provide state symbols.
H+(aq) + OH-(aq) ——> H2O(l)
2H+(aq) + O2-(aq) ——> H2O(l)
Define formulation
- A formulation is a mixture that has been designed to do something useful.
- It is formed by mixing together several different substances in carefully measured quantities to ensure the product has the required properties.
Write the formula for moles. State it rearranged.
Mol = mass / relative atomic mass
Mass (g) = Mr x Mol
Mr = mass / mol
Mass
Mol. Mr
(Moles are the same as number of moles (N))
State Avogadro’s constant
A mole of a substance is 6 x 1023 particles
State the formula for concentration. State it rearranged.
Conc (C) = number of mol (N) / volume (dm3)
N = C x V (dm3)
V = N / C
N
C V
What colour flame does a Ca2+ ion cause in a flame test?
Brick red
What colour flame does a Li+ ion cause in a flame test?
Crimson
What colour flame does a Na+ ion cause in a flame test?
Yellow/orange
What is a precipitate?
A solid formed on mixing two solutions
What is meant by the term hydrated?
When a substance contains water of crystallisation
Describe how a pure, dry sample of hydrated calcium chloride may be prepared from solid calcium carbonate and hydrochloric acid. (6)
- place hydrochloric acid in a beaker/conical flask
- add calcium carbonate until in excess/no more gas given off
- filter
- heat filtrate to half volume
- allow to cool and crystallise
- filter off crystals
- dry between two sheets of filter paper/in a desiccator/in a low
temperature oven
What is potable water?
Drinkable water
Why is chlorine used in water treatment?
To kill microbes (bacteria and viruses)
What substance is used in coagulation/sedimentation?
Aluminium Sulfate
What is meant by the term saturated solution?
A solution in which no more solute will dissolve at a particular temperature
How do you work out the Rf value in chromatography?
Distance moved by substance / distance moved by solvent (solvent front)
What colour flame does a K+ ion cause in a flame test?
Lilac
What colour flame does a Cu2+ ion cause in a flame test?
Blue-green
What colour precipitate does a Cu2+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
Blue ppt in excess sodium hydroxide
Deep blue ppt in excess ammonia solution
What colour precipitate does a Fe2+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
Green ppt
What colour precipitate does a Fe3+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
Red-brown ppt
What colour precipitate does a Mg2+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
White ppt
What colour precipitate does a Al3+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
White ppt in excess sodium hydroxide
But
Dissolves in excess ammonia solution
What colour precipitate does a Zn2+ ion cause when dissolved and added to sodium hydroxide/ammonia solution?
White ppt
Which dissolves in both solutions
What colour precipitate does a Cl- ion cause when dissolved and added to silver nitrate solution?
White ppt
What colour precipitate does a Br- ion cause when dissolved and added to silver nitrate solution?
Cream ppt
What colour precipitate does a I- ion cause when dissolved and added to silver nitrate solution?
Yellow ppt
What colour precipitate does a SO4- ion cause when dissolved and added to barium chloride solution?
White ppt
What is the test for a CO3- ion?
Add dilute acid to the solid and test gas with limewater
Bubbles, limewater turns milky from colourless
What colour is copper nitrate solution?
Blue
Outline the processes in creating potable water from water in reservoirs (3)
Filtration —> Sedimentation/Coagulation —>Chlorination
Outline the process of creating potable water from seawater (1)
Distillation/desalination
Why is aluminium sulfate used in sedimentation?
It is a coagulant
What wire is required during a flame test?
A nichrome wire
What is the formula of Methane?
CH4
What colour is iodine in solution
Red-brown
What colour is bromine in solution ?
Orange
What is the name given to Calcium Hydroxide solution?
Limewater
What is the definition of empirical formula?
The empirical formula is the simplest whole number ratio of the atoms of each element in a compound
What is the molecular formula?
The molecular formula is the actual number of atoms of each element in a molecule.
What is the definition of degree of hydration?
The degree of hydration is the number of moles of water of crystallisation chemically bonded in 1 mole of the compound.
What is the definition of a salt?
A salt is a compound formed when some or all of the hydrogen ions in an acid are replaced
by metal ions or ammonium ions.
What is the definition of water of crystallisation?
Water of crystallisation is water that is chemically bonded into the crystal structure.
What is the approximate size of the diameter of an atomic nucleus?
2 × 10-15m