Elements Of Life Flashcards
What is the atomic number
Protons and electrons
What is the mass number
Protons and neutrons
What is an isotope
Atoms of the same element with different neutron numbers
What is relative isotopic mass
Atoms isotopic mass compared with 1/12 of carbon-12 mass
What is relative atomic mass
Average mass of an atom of an element based on percentage abundancies of isotopes
What is relative formula mass
Mass of atom compared to another
What is relative molecular mass
Average mass of one molecule to 1/12 carbon-12 mass
When can’t relative molecular mass be used
If the bond is ionic
What is a mole
A substance amount containing 6.02x10^23 particles of substance
How is water crystallisation calculated
Using a table Mass Mr Moles Ratio And using the anhydrous mass of the element in the compound with water
What is molecular formula
Expression of number and type of atoms in a single substance
What is empirical formula
Simplest formula, ratio of elements in compound (once found moles of all divide all by the smallest mole)
How do you find the percentage composition of an element in a compound
Workout the relative formula mass of compound
Divide the elements Ar by the compounds Ar then x100
How do you find substance masses
Calculate the number of moles in the compound moles = conc x vol
Then calculate the mass using mass = mol x Mr
How do you do a titration calculation
Write the balanced symbol equation
Workout the moles of the neutraliser
Workout the moles of the element dissolved using the ratio and moles of the neutraliser
If need to scale up the volume e.g 25cm^3 to 1000cm^3 (25x40)=1000 so do the moles of the dissolved element x 40
Find the mass of the dissolved element
Workout the percentage purity actual(g)/all(g) x100
What is the percentage purity calculation
Actual (g) / all (g) x100
How do you make a standard solution
Workout number moles of solute needed
Workout number grams of solute needed (mass)
Weigh solute mass (first beaker then add mass)
Add small amount distilled wager to beaker dissolve solute then put in volumetric flask
Do rinsing did beaker and did
Too up flask to amount using pipette
How do you do a titration
Measure alkali into flask with indicator
Titration find neutralisation point
Do again accurate without indicator using same acid amount - titre
What is the equation to make a standard solution from a more concentrated one
Volume to use = final conc / initial conc x vol needed
Measure into volumetric flask top up with distilled water to needed volume
In s-sub shell how many orbitals are there and how many electrons does it hold
Has 1 s-orbital that holds 2 electrons
How many orbitals are there in the p-sub-shell and how many electrons can this hold
Had 3 p-orbitals that hold 6 electrons
In the d-sub-she’ll how many orbitals are there and how many electrons can it hold
Has 5 d-orbitals and can hold 10 electrons
In the f-sub-shell how many orbitals are there and how many electrons can it hold
There are 7 f-orbitals that can hold 14 electrons
Why are orbitals singly filled before pairing them
To keep the electrons as far apart as possible
How can you use the periodic table to find the outer sub-shell of an element
The block it is in e.g s is the last shell letter and the period that it is in is the small number
What were the Greeks contribution to discovering atoms
Matter made of invisible particles
What were the contributions John Dalton made to discovering atoms
Atoms are solid spheres make up different element
What were the contributions JJ Thomson made to discovering atoms
Plum pudding model, measured charge and mass
Discovered electrons
What were the contributions Rutherford made to discovering atoms
Saw alpha particles mainly not deflected by gold particles, mainly empty space with electron cloud
Later found that positive protons, different atoms have different protons
What were the contributions James Chadwick made to discovering atoms
Discovered neutrons
What were the contributions Bohr made to discovering atoms
If electrons in clouds, would spiral down, atom would collapse. Discovered shells, orbits that energy emitted/absorbed when electron move, fixed radiation frequency. Explained inert elements, why full shells are stable
Why is the 4s filled before the 3d sub shell
What are the exceptions
As it is closer to the nucleus
Copper - 3d^10 4s^1 is more stable to have full shell
Chromium - 3d^5 4s^1 is more stable half full shell, all orbitals have one electron, rather than fill 4s
What is nuclear fusion
Very high temperature, two light nuclei make heavier one. High pressure needed
What is covalent bonding
Non-metallic elements bond by sharing electrons. Atoms held together as positively charged nuclei attracted to negatively shared electrons
What is a dative covalent bond how is it drawn in a bond with the molecules
Contain lone pairs
When drawing the bonds the arrow points away from the atom donating the electron
What is an electron deficient molecule
AlCl3
How much does a lone pair ‘squash’ the structure by
2.5 degrees
What is simple molecular bonding, examples and what features does it have
Covalent molecular
Shared electron pairs. Weak intermolecular and strong covalent with non-metals e.g H2O, I2
Low melting/boiling point
No electrical conductivity
Insoluble in water (except oxygen, carbon dioxide, C2H5OH)
Soft
What is metallic bonding, examples and what features does it have
Giant lattice
Positive metal ions with a sea of delocalised electrons, force of attraction e.g Cu, Zn, K
High melting/boiling point expect mercury
Has electrical conductivity
Insoluble in water
Hard except for group 1 metals and mercury
What is ionic bonding, examples and what features does it have
Giant lattice
Positive and negative ions has electrostatic forces of attraction e.g NaCl, MgO
Metal and non metal except AlCl3, AlBr3, ACI3
High melting/boiling point
Has electrical conductivity when dissolved or molten (ions free)
Hard but brittle
What is giant covalent bonding, examples and what features does it have
Giant lattice
Two positive nuclei and two atoms attraction with same shared electrons e.g graphite, sand (SiO2), diamond
Non-metals
High melting/boiling point
No electrical conductivity except from graphite
Hardness high except graphite
What bond is it when there is 2 bonding pairs and no lone pairs and example
Linear
180 degrees
BeCl2
What bond is it when there is 3 bonding pairs and no lone pairs
Trigonal planar
120 degrees
AlCl3
What bond is it when there is 4 bonding pairs and no lone pairs
Tetrahedral
109.5 degrees
NH4, CH4
What bond is it when there is 5 bonding pairs and no lone pairs
Trigonal bypyramid
90 degrees and 120 degrees
PF5, PCl5
What bond is it when there is 6 bonding pairs and no lone pairs
Octahedral
90 degrees
SF5
What bond is it when there is 3 bonding pairs and 1 lone pair
Pyramidal
107 degrees
NCl3, NH3
What bond is it when there is 2 bonding pairs and 2 lone pairs
V-shaped or bent
104.5 degrees
H2S, H2O
What line is used to show a bond in plane of paper
Full block line
What line is used to show a bond behind paper plane
Dotted line
What line is used to show a bond in front of paper plane
Block triangle
What is a giant ionic lattice
Large repeating structure, minimises repulsion, maximises attraction
What happens to melting/boiling point across period 3, what happens from silicon to phosphorus
Increase across period
Falls at silicon to phosphorus, as bonds between particles in phosphorus weaker, easier to overcome than silicon
What happens across any period
Atomic radius decrease, nuclear charge/protons increase, no extra energy levels, no shielding
What happens in period 2 and 3 and after 3 to the densities
Period 2 and 3 densities increase across period except gases rose to maximum in group 3 and then fall
What happens after 92-uranium to the nuclear force between protons
Strong nuclear force holds protons together till around 92-uranium,overcome repulsion, all isotopes unstable
What did Mendeleev do with the periodic table
Combined atomic mass ideas and reactivity, left gaps for elements
1886 germanium discovered proved it
Which group is the alkali metals
Group 1
Which group is the alkali earth metals
Group 2
What happens down group 1 and 2 to the elements
More reactive down group as electrons further from nucleus due to more shielding
Why are electrons harder to loose across the period
Less reactive across period, stringer nucleus electrons harder to loose
What are the properties of metals
Shiny
Malleable
Conduct electrons and heat
What are the properties of non-metals
Poor conductors of heat and electrons
What is ionisation enthalpy
Energy to remove an electron from outermost atom shell. Always positive, as energy needed to break attraction
X(g) -> X^+ (g) + e^-
What happens to the ionisation enthalpy across a period
Larger ionisation enthalpy as stronger nucleus, smaller atomic radius so harder to loose electron
What happens between nitrogen and oxygen to cause the slight decrease as shared orbital
Electrostatic repulsion
Why is there a lower first ionisation at boron
Fist electron removed from p sub-shell, higher in energy (further from nucleus)
Why is there a lower first ionisation at oxygen
Electrons start to pair in orbitals, repel, less energy required to remove electron
Why is the second ionisation higher
Fewer electrons but same protons so stronger attraction in second so need more energy to remove an electron
X^+(g) -> X^2+(g) + e^-
What is formed when an S block oxide/hydroxide react with acid
What is it used for
Salt and water
MO/OH + acid -> salt + water
Has neutralising effect, used as fertilisers
What are the properties of the S block
Soft
Low melting/boiling point
What does group 2 metal and water form
Not usually on own group 2 metal react with water
2M + 2H2O -> 2M(OH)2 +H2
Water added to oxide to form hydroxide alkaline solution formed as group 2 are bases
What is the equation when S block metal carbonate heated and what is this process
CaCO3 -> CaO +CO2
Thermal decomposition
What happens to thermal stability down a group, how is it explained
Harder to decompose, thermal stability increases
Explained in charge density of cation charge concentration
Does a smaller 2+ ion polarise a carbonate ion better, what effect does polarisation have on the ion when heated
Smaller 2+ ion, higher charge density can polarise negative charge cloud round carbonate ion, less stable, easily broken when heated
What happens to group 2 hydroxide solubility down the group
Increases, for most group 2 compounds with -1 charge
What happens to group 2 carbonate solubility down group
Decreases, for most group 2 metals compounds with -2 charge
What is a base and what bases are there and what is a soluble base called
Substance accepts hydrogen ions
Proton acceptor
Metal oxide, metal hydroxide, metal carbonate
A soluble base - alkali
What is the acid + metal reaction
Acid + metal -> salt + hydrogen
What is acid + metal oxide reaction
Acid + metal oxide -> salt + water
What is the acid + metal hydroxide reaction
Acid + metal hydroxide -> salt + water
What is the acid + metal carbonate reaction
Acid + metal carbonate -> salt + carbon dioxide + water
What is an acid
Substance that donates hydrogen ion H^+ in chemical reaction
Proton donors
What is the Brönsted Lowry theory
Acids are proton donors, bases are proton acceptors
Hydrogen theory transfer
What is the neutralisation ionic equation
Alkali reacts with acid, salt made - neutralisation reaction
H^+(aq) + OH^-(aq) -> H2O(l)
What reactions with OH^- in ionic precipitation and what colour precipitates are formed
Cu^2+ +OH^- -> Cu(OH)2 blue
Fe^2+ +OH^- -> Fe(OH)2 green
Fe^3+ +OH^- -> Fe(OH)3 orange/brown
What reactions with Ba^2+ in ionic precipitation and what colour precipitates are formed
SO4^2- +Ba^2+ -> BaSO4 white
What reactions with Pb^2+ in ionic precipitation and what colour precipitates are formed
Pb^2+ +2I^- -> PbI2 bright yellow
What reactions with AgNO3/Pb(NO3)2 in ionic precipitation and what colour precipitates are formed
Halides Cl^- + AgNO3 -> AgCl Cl^- + Pb(NO3)2 -> PbCl white Br^- + AgNO3 -> AgBr Br^- + Pb(NO3)2 -> PbBr cream I^- + AgNO3 -> AgI I^- + Pb(NO3)2 -> PbI yellow
What test can you use to test which halide precipitate is formed
Mix with dilute NH3
Cl^- dissolves
Br^- partially soluble
I^- insoluble
When are bases formed from group 2 oxides
When hydroxides added to water they form alkaline solutions
What are the insoluble solids
Barium
Calcium
Lead
Silver sulfate
In the electromagnetic spectrum when does frequency increase
From radiofrequency -> gamma rays
In the electromagnetic spectrum when does wavelength increase
Gamma rays -> radiofrequency
In the electromagnetic spectrum when does energy increase
Radiofrequency -> gamma rays
What is the absorption spectra
Particles absorb some emitted radiation, light analysed from stars missing certain frequencies
Absorption lines are black, missing light frequencies absorbed by chromosphere particles
What is the emission spectra
Atoms/molecules/ions in chromosphere absorb energy, raised from ground state - excited states. Lose extra energy, emit electromagnetic radiation, detecting emission spectra. Appear as coloured lines on black background
What is the balmer series
Hydrogen emission spectrum (visible)
What is the Lyman series
Hydrogen emission spectra (UV light)
What is the atomic structure
Light from stars not continuous, has lines corresponding to absorption/emission of specific frequencies of light
What does an energy level diagram show
Emission spectra
Larger energy gap deltaE the higher the frequency of electromagnetic radiation emitted
What does E=hf workout
Photon light energy given off as electron falls
h - Planks constant - 6.63x10^-34?JHz(Js^-1)
What is spectroscopy
Study how light, matter interact so can understand atoms electronic configuration
What is the wave model of light
Wavelength, frequency behaviour
Wave of light travel distance certain time with speed, c = (3x10^8ms^-1)
Use c=wavelength x frequency
What is the particle model of light
Light considered as stream of energy packets - photons. Energy of photons related to light position on electromagnetic spectrum
What are the flame test and the colours
Ion Colour Li^+ Bright red Na^+ Yellow K^+ Lilac Ca^2+ Brick red Ba^2+ Apple green Cu^2+ Blue green
How is the absorption and emission spectra linked
Energy/frequency of absorption black lines from 1->2 is the same as the emission coloured lines from 2->1
How can mass spectra be used to calculate relative atomic mass of relative abundance
Each ion calculates from each peak height
Calculate RAM - relative isotopic mass x relative abundance / 100 + ..
No units as relative
How can relative abundances be calculated
E.g RAM of antimony = 121.8 Has two isotopes, antimony-121 and -123 Ar = 121 x ?/100 + 123 x (100-?)/100 (x100) 12180 = 121? + 123(100-?) (Expand) 12180 = 121? + 12300 - 123? (Group) 123? - 121? = 12300 - 12180 2? = 120 ? = 60 So antimony-121 = 60% and antimony-123 = 40%
