Studied by 4 people
Define elements
Substances with 1 unique atom which can not be further broken down
Define compounds
Consists of atoms, chemically bonded together in a fixed ratio. Chemical and physical properties are completely different than those of the component elements
Define a homogenous mixture
A mixture of multiple elements not chemically bonded together with uniform composition (eg. air)
Define a heterogenous mixture
Multiple elements not chemically bonded together in un-uniform composition (eg. oil and water)
Define filtration
separation by a pouring a solution through a membrane and collecting the solid (reside) and the filtrate passing through
Define distillation
is used to separate a solute from a solvent. As they have different boiling points, you can evaporate and trap the solvent, leaving the solute. The solvent can be condensed back to its original state.
Define paper chromatography
substance is placed on paper with water. As the water is absorbed substances are separated across the paper
What is the difference between a solute and a solvent
solute = the substance that dissolves
solvent = the dissolver
What is the kinetic molecular theory?
when temperature increases, so does kinetic energy causing particles to move more and separate
what is the equation for kinetic energy?
Ek = ½ mv²
How do you go from gas to liquid and back?
gas → liquid: condensation
liquid → gas: evaporation
how do you go from liquid to solid and back?
Solid → liquid: melting
liquid → solid: freezing
how do you go from a gas to a solid and back?
Gas → solid: deposition
solid → gas: sublimation
what are the features of a solid?
particles are closely packed together and vibrate in place
strong inter-particle forces
fixed volume
fixed shape
what are the features of a liquid?
particles are more spread
inter-particle forces weaker, particles slide over each other
shape depends on container
fixed volume
what are the features of a gas?
particles are fully spread
inter-particle forces are negligible, particles move freely
no fixed shape
no fixed volume
Define boiling point
A fixed temperature for every element when:
vapour pressure = atmospheric pressure
vapour pressure increases with temperature because more particles enter vapour state with extra kinetic energy
Why is temperature constant at the boiling point?
because the extra energy is being used to separate particles rather than increase temperature
Define evaporation
happens at a range of temperatures below the boiling point at the surface when particles enter vapour state
What is the calculation for kelvin?
Kelvin = celcius + 273.15
What happens at 0K
this is absolute zero when all movement stops
Define atoms
atoms are the smallest matter in the universe and can not be further broken down. They are defined by their unique proton numbers
What does the Bohr model of carbon look like?
What happens as energy shells get farther from the nucleus?
energy becomes higher, but the shells converge so the difference in energy between shells decreases
What is the shorthand notation?
What is the nucleon number?
neutrons + protons
What is the atomic number?
the number of protons in the nucleus (AKA proton number)
Why are neutrons important?
because they maintain stability of the nucleus. They prevent protons from repelling each other
What is the mass number?
An average of all masses of an element (incl. isotopes). This is roughly equal to the nucleon number
Define ions
An element with a different number of electrons than protons. They have drastically different chemical properties than its original element
what is a cation?
positively charged ion
what is an anion?
negatively charged ion
what are isoelectronic species?
particles with the same number of electrons, even if they do not have the same number of protons
What are isotopes?
atoms of the same element with a different number of neutrons
what does the more ‘abundant’ isotope mean
the more isotopes with occurs more often in nature
what is a radioisotope
an isotope which releases radiation to maintain stability of the nucleus
What are the changes in properties for an isotope
physical: boiling/melting point, density and mass
chemical: none
What are the different forms of energy?
heat, light and electricity
What happens when energy is emitted on an atom?
It is absorbed, causing an electron to excite to a higher energy shell. This is unstable so it will eventually drop back down to ground state causing a photon to emit
how do you calculate the energy of a photon?
E(photon) = E(electron)
E(photon) = h (planck’s constant) x f (frequency)
Which equation combines wavelength, frequency and speed of light?
c = f x λ
what is a continuous spectrum?
shows all possible wavelengths merged together
what is a line spectrum?
only shows specific wavelengths
Define orbital
a region around the nucleus where the electron is 90% likely to be.
All orbitals are the same, they only differ in space.
There are 2 electrons per orbital
How do you draw an orbital diagram?
How many orbitals are there in each sublevel?
S: 1 (2 electrons)
P: 3 (6 electrons)
D: 5 (10 electrons)
F: 7 (14 electrons)
Define degenerate orbitals
orbitals with the same amount of energy
How many sublevels are there in each energy level?
1: S
2: S and P
3: S, P and D
4: S, P, D and F
How can you tell the group and period from the electron configuration?
The last number tells you the period and the number of electrons tells you the group:
eg. if it ends in 4s1, it is in period 4 group 1
How do you draw an S orbital?
How do you draw a P orbital?
How do you fill orbital diagrams?
First fill each orbital with 1 electron, then start adding the second
What is the order of filling up?
the S fills before the D but when ionising, electrons are removed from S first
What are the exceptions to the order of filling up electrons?
Chromium and copper
what is the electron configuration of chromium?
[Ar]4s1 3d5
what is the different between the shorthand and complete electron configuration?
Shorthand: [last noble gas] any electrons in this period
complete: shows all electrons
Why do some elements deviate from the expected electron configuration?
Because there is extra stability in half-filled orbitals
What is the electron configuration of copper?
[Ar] 4s1 3d10
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