SAC Revision Flashcards
What is an element?.
pure substance that only contains one type of element.
What is an Isotope?
Variation of an element with the same atomic number/number of protons, but different mass number/number of neutrons
What is an ion?
an atom that has lost or gained electrons to become a charged particle (protons =/ electrons)
What is atomic number?
number of protons in an atoms nucleus, the atomic number is the top number on a period box
What is mass number?
mass of an atom, is equal to protons + neutrons
In what context are the amount of protons and electrons the same?
in a particle with no charge, particle/atom that hasn’t lost/gained electrons
What are the 5 the periodic trends?
McCAFE
Metallic Character, Core Charge, Atomic Radius, First Ionisation Energy and Electronegativity
What is Metallic Character and how does it increase?
degree in which an element is shiny and conducts electricity
increases ↙
What is Core Charge and how does it increase?
The pull of the positive nucleus on valence electrons
increases ⭢
How is core charge calculated?
protons - inner shell electrons = core charge
What is Atomic Radius and how does it increase?
the distance from the centre of an atom to the valence electrons
increases ↙
What is First Ionisation Energy and how does it increase?
the energy required to remove the first valence electron
increases ↗
What is Electronegativity and how does it increase?
ability of an element to attract shared electrons towards itself
increases ↗
What is covalent bonding?
sharing of electrons between non-metals
What is the Lewis Structure?
digram representing bonding with dots and crosses
What is Structural Formula?
diagram representing bonds with lines
What are the 4 molecular shapes?
linear, bent, pyramidal and tetrahedral
What does the linear shape look like?
o-o
What does the bent shape look like?
o o
\ /
o
What does the pyramidal shape look like?
. o
/ | \
o o o
What does the tetrahedral shape look like?
. o
|
. o
/ | \
o o o
What is the VSEPR theory?
theory that states that electrons pairs repel each other so they will move as far apart as possible, thus creating different shapes
What is polarity?
property of having one partial positive and one partial negative charge
What is a polar molecule?
a molecule that displays polarity and has a partial positive and negative charge
What is a non-polar molecule?
a molecule that has no overall charge
What is the relation between polarity and molecular shape?
Symmetrical molecules tend to be non-polar and asymmetrical molecules tend to be polar
due to equal charges on both sides cancelling each other out
What are the 3 main types of intermolecular bonding?
hydrogen bonding, dipole-dipole attraction and dispersion forces
What is hyrdrogen bonding?
type of intermolecular bond occurs when hydrogen bonds to nitrogen, oxygen or fluorine (H-NOF) on one molecule, as well as a neighbouring one
What is dipole dipole attraction?
a type of intermolecular bond that occurs when there is a permanent partial charge/polarity
What are dispersion forces?
a type of intermolecular bond that occurs due to electrons always moving, causing temporary dipoles, which attract and bond to other temporary dipoles
What is the difference between intermolecular and intramolecular bonding?
intermolecular is between molecules and intramolecular is between atoms
What are the strengths of the types intermolecular and intramolecular bonds in relation to each other?
covalent bonding>hydrogen bonding>dipole dipole attraction>dispersion forces
What are molecular properties often determined by?
intermolecular forces/bonding
What is the correlation between energy and bond strength?
the stronger the intermolecular bond the more energy required to break the bond
What are melting/boiling points?
the temperature in which a solid becomes a liquid or a liquid becomes a gas
How are melting/boiling points related to structure and bonding types?
If the structure and bonding type is stronger and harder to break then the melting/boiling point will be higher as the molecule needs to gather more energy via heating break bonds and change states
What is conductivity?
the ability to allow electric current to flow though
What is needed for conductivity to occur?
free moving electrons, which are not present in solids, thus structure needs to be broken or allow free moving electrons
What is an allotrope?
the different physical form of an element due to different structural atom arrangements
What are diamond and graphite allotropes of?
carbon
How do diamond and graphites structures differ?
diamonds structure is more solid and stable, whilst graphite has a 2D layer arrangement making it easier to break layers apart
How does diamond and graphites conductivity differ?
diamonds are not conductive as they have no free moving electrons, whilst graphite’s structure allows for free moving electrons
What is metallic bonding?
a type of intramolecular bonding in which metals attract each other and form a strong bond that is characterised by the sea of delocalised electrons
What are the 4 key properties of metals?
lustre, malleability, ductility and conductivity
What is lustre and how does it relate to metallic bonding?
the property of appearing shiny or glossy, which is due to the delocalised surface electrons being able to reflect light
What is malleability and how does it relate to metallic bonding?
the ability to be bent and hammered without breaking, which is caused by the strong bond and the freely moving electrons allow it to adapt to change in shape
What is ductility and how does it relate to metallic bonding?
the ability to be drawn/thinned out without breaking which is caused by the strong bond and free moving electrons being adaptable to shape changes
What is conductivity and how does it relate to metallic bonding?
the ability to allow electrical current or heat to flow though, which is caused by the electrons being free moving and able to create a chain reaction in order to pass the electricity/heat down
What are the 3 main types of oxidation reactivity?
acid, water and oxygen
What types of oxidation reactivity are applicable to the most elements?
oxygen>acid>water
What two oxidation reactions always include hydrogen gas?
water and acid
What is oxidation?
a chemical reaction in which a chemical loses electrons
What is an ionic bond?
a type of intramolecular bonding between metals and non-metals
What is a cation?
a positively charged atom that has lost electrons
What is an anion?
a negatively charged atom that has gained electrons
What are the 3 properties of an ionic compound?
brittle, hardness and liquid conductive
Why are ionic compounds brittle?
the diagonal 3D structure creates a strong bond, however, if misaligned the charges will repel each other thus easily breaking
Why are ionic compounds hard?
the diagonal 3D structure creates a strong bond that cannot easily be broken
Why are ionic compounds only conductive in liquid?
this is due to the structure, as to be conductive requires free moving electrons which are only present in its liquid state and not the solid as the structure is too strongly bonded to move
How do anions change in an equation?
end in ide eg fluorine -> fluoride
What is a polyatomic ion?
ion that contains one or more atoms
What is precipate?
an insoluble product made when substances in a solvent are mixed and swap partners causing a change in state from aq to s
What are the steps to write and balance an equation?
- write reactant formula
- swap partners (if necessary)
- write product formula
- balance equation and ensure reactants = products
What does SNAPE stand for?
water soluble elements
sodium, nitrate, ammonium, potassium and ethanoate
What is Help Protect PRAM stand for?
critical elements
helium, phosphorus, post transition metals, rare earth elements and metalloids
What is a circular economy?
continuous cycle that focuses on reuse and repurposing of materials to ensure a more sustainable future
What steps does a circular economy include?
natural resources ->
take, make/remake, distribute, use, sort, recycle (repeat)
