chemistry section: A

what is the charge of the proton, neutron and electron?

proton: +1 neutron: 0 Electron: -1

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what do the periods on the periodic table relate to?

which energy shell the valence electrons are in

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what do the groups of the periodic table relate to?

Refers to how many valence electrons are in the outer shell

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what are the masses of electrons, neutrons and protons?

electrons: 1/1836 neutrons: 1 protons: 1

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what is the spin of protons, neutrons and electrons

1/2

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what particles are in the nucleus?

protons and neutrons. They are held together by a strong nuclear force which overcomes the replusive force between the protons.

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define atomic number, Z?

how many protons are in the nucleus - elements are identifed by their atomic (proton) number

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define relative atomic mass, Mr

weighted mean mass of an element compared with 1/12 of the mass of carbon 12.

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define mass number

total number of protons and neutrons in the nucleus.

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define isotope

atoms of the same element with different numbers of neutrons

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explain how a mass spectrometer works.

substance is placed into a vacuum and vaporised. Sample is then bombarded with electrons - causing ionisation. The ions are then accelerated using an electric field which are then deflected by a magnet according to their mass.

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what does the amount of deflection by a mass spectrometer depend on?

mass to charge ratio - M/Z ratio. The greater the mass - the smaller the deflection

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what are the isotopes of hydrogen with two and three neutrons called? and give their symbols.

2 = deuterium (D) 3= tritium (T)

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define mole

a mole of a substance contains 6.022 x 10^23 molecules (contains avogadro's number NA/L)

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what is the atomic mass unit (amu)?

1.6605 x10-27 kg

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does the molar mass have units?

yes. The molar mass is the relative atomic mass (unitless) X g/mol

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what is the equation for working out moles:

moles = mass (g) / relative molecular mass (g/mol)

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What is the Aufbau principle?

this is the principle that the lowest energy orbitals are occupied first

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what is the Pauli principle

no two electrons in an atom can have the same four quantum numbers. The implication - max. of 2 electrons can share each orbital, with the same number of values of n, l, ml but different spin (ms= +1/2 and -1/2)

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define the uncertainty principle

this an implication of decribing the electron as a WAVE. it means that its postition and momentum (energy) cannot simultaneously be determined.

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define orbital

this is where the electron is MOST PROBABLY located

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What is the principal quantum number (shell) and how is it denoted?

shells are of increasing size (or average distance from the nucleus). The principal quantum number is denoted as n. It tells you about how big the orbital is, or how far (on average) an electron occupying it is from the nucleus.

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define subshell

within each shell (n) there are different subshells - different arrangements of electrons within a shell. These are labelled according to their shape - s,p,d,..

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what is the second quantum number called and how is it denoted?

angular momentum quantum number, l. This tells you about the SHAPE of the orbital - l=0 is an s orbital. l=1 is a p orbital l=2 is a d orbital

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how many orbitals are in a p subshell

3 --> Pz, Py, Px

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how many orbitals are in a d subshell?

5 --> Dxy , Dyz , Dzx, Dx - y , Dz

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what is the third quantum number and how is it denoted?

magnetic quantum number: ml: this quantum number tells you about the orientation of the orbital. e.g. if l=1 ml = -1, 0, +1 denoting Px, Py and Pz

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how are the shapes of orbitals calculated?

they are calculated from wave functions

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what is a node?

this is a position where the wavefunction = 0. This is where there is zero probability of the electron being found there. the wave function has a different sign either side of the node (different wave functions)

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how do wave functions explain the order of energies of the orbitals?

Energy is related to distance from the nucleus. further away = higher energy. wavefunctions are used to calculate the RADIAL DISTRIBUTION FUNCTION of the orbital - how the probability of finding the electron varies with distance from the nucleus.

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describe s orbitals

s orbitals are spherical, with the same sign of wavefunction across the whole of the boundary surface.

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what is the spin quantum number Ms?

electrons either spin clockwise (+1/2) or anticlockwise (-1/2)

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explain Hund's rule of maximum multiplicity

if two or more electrons have the SAME energy, then electrons will spread out to occupy the maximum possible number of these, maximising the number of parallel spins.

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why does Hund's rule apply?

1) electrons occupying separate orbitals minimises ELECTROSTATIC REPULSION. 2) electrons have lower energy if they are parallel - SPIN CORRELATION

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what determines the CHEMICAL REACTIVITY of an element?

The valence electrons

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What determines the biological role of an element?

valence electrons - s block elements = stable cations e.g. Na+ as electrolytes in the blood. p block elements form multiple bonds e.g. C in sugars and proteins. D block elements have variable oxidation states e.g. cytochrome C oxidase

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chemistry section: A

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