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)