Flashcards in Topic 1 - Key Concepts Deck (28)
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1
define aqueous
dissolved in water
2
symbol for ammonia
NH3
3
symbol for oxygen
O2
4
symbol for chlorine
Cl2
5
symbol for ammonium ions
NH4 +
6
symbol for nitrate ions
NO3-
7
symbol for carbonate ions
CO3 2-
8
symbol for sulphate ions
SO4 2-
9
how do you do ionic equations from a full chemical equation
break up aqueous products and reactants into ions
cross out what is the same on both sides
re write with remaining ions
10
define hazard and risk
a hazard is anything that has the potential to cause harm or damage
the risk associated with that hazard is the probability of someone or something being harmed if they are exposed to that hazard
11
discuss John Daltons model of the atom
at the beginning of the 1800's (19th century) Dalton described atoms as solid spheres for the different elements
12
discuss JJ Thompsons model of the atom
In 1897 he concluded from his experiments that atoms were not solid spheres
- his measurements of charge and mass showed that an atom must contain even smaller, negatively charged particles called electrons
- the 'solid sphere' idea of atomic structure had to be changed
- new theory was the plum pudding model which was a positively charged pudding with electrons throughout
13
what was Rutherford's model of the atom
there is a tiny positively charged nucleus at the centre surrounded by a cloud of negative electrons and most of the atom is empty space
14
what was the refined Bohr model of the atom
Scientists realised that electrons in a cloud around the nucleus of an atom would cause it to collapse because they would be attracted to the positive nucleus
Niels Bohr proposed a new model of the atom where all the electrons were contained in shells
Bohr suggested that electrons can only exist in fixed orbits or shells and not anywhere in between.
each shell has a fixed energy
15
define isotope
different forms of the same element which have the same number of protons and electrons but a different number of neutrons
the same atomic number but different mass numbers
16
define relative atomic mass
the relative atomic mass of an element is the average mass of one atom of the element compared to 1/12 of the mass of one atom of carbon-12
17
how does Dimitri Mendeleev's version of the periodic table compare to ours
Mendeleev:
- based on their properties and properties of their compounds
- order of atomic mass
- similar chemical properties in columns
Ours:
- order of atomic number
- similar chemical properties
- groups with outer shell electrons
- periods
18
what is the overall charge of any ionic compound
0 because the charges balance each other out
19
what is ionic bonding
when a metal and non metal react together
the metal atom loses electrons to form a positive ion (cation) and the non-metal gains electrons to from a negative ion (anion)
these oppositely charged ions are attracted together by electrostatic forces of attraction
20
how do you show an ionic bond
dot and cross diagram
21
describe the structure of ionic compounds
- giant ionic lattice structures
- the ions form a closely packed regular lattice of oppositely charged ions
- there are very strong electrostatic forces of attraction between oppositely charged ions in all directions
22
describe the properties of ionic compounds
- high mp and bp due to strong attractions between the ions so it takes a large amount of energy to overcome this attraction
- solid ionic compounds don't conduct electricity because the ions are fixed in place and can't move
- molten ionic compounds can conduct because the electrons are free to move and carry a current
- many dissolve easily in water, the ions separate and are all free to move in the solution so they'll carry an electric current
23
describe the properties of simple molecular substances
- substances containing covalent bonds usually have simple molecular substances
- the atoms within the molecules are held together by very strong covalent bonds but the forces of attraction between these molecules are very weak
- to melt or boil a simple molecular substance you only need to break these feeble intermolecular forces and not the covalent bonds so mp an bp's are very low because the molecules are easy to part from each other
most molecular substances are gases or liquids at room temperature
- as molecules get bigger the strength of intermolecular forces increases so more energy is needed to break them and the melting and boiling points increase
- molecular compounds don't conduct electricity because they don't contain any free electrons or ions
24
describe the properties of giant covalent structures
- high mp and bp as all the atoms are bonded to each other by strong covalent bonds and a lot of energy is needed to break these bonds
- don't conduct electricity (apart from graphite and graphene) because they don't contain charged particles
- they aren't soluble in water
25
what are fullerenes
- molecules of carbon shaped like closed tubes or hollow balls
- mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons
- can be used to 'cage' other molecules
- the fullerene structure forms around another atom or molecule which is then trapped inside
- this could be used to deliver a drug directly to cells in the body
- fullerenes have a huge surface area so they could help make great industrial catalysts
- individual catalyst molecules could be attached to the fullerenes, the bigger the surface area the better
26
what are nanotubes
- are also fullerenes
- they are like tiny cylinders of graphene so they conduct electricity
- have a high tensile strength so don't break when stretched and can be used to strengthen materials without adding much weight
- for example they can be used to strengthen sports equipment that needs to be strong but lightweight like tennis rackets
27
what is buckminsterfullerene
- molecular formula C60
- forms a hollow sphere made up of 20 hexagons and 12 pentagons
- it is a stable molecule that forms soft brownish-black crystals
28
