Elements of Life Flashcards
How did the structure of the atom develop over time?
First was plum pudding model
Disproved by Geiger marsden
Bohr model - protons, neutrons and electrons
Evidence for shells - ionisation enthalpies and spectra
What reaction conditions are needed for fusion reaction?
High temperature and pressure
How do covalent bonds work?
There is a balance between repulsive forces between the nuclei and there is attractive forces between the nuclei and electrons
What is the bond angle of a tetrahedral molecule?
109.5
What is the bond angle of a pyramidal molecule with a lone pair?
107
What is the bond angle of a bent molecule with two lone pairs?
104.5
How do giant ionic compounds work?
Overall attraction in a lattice made of attraction beteeen I one of different charge shd repulsion of ions of the same charge
Explain the Trend in meltibg points in period 2 and 3
In period 2 meltibg point increases until carbon/silicon (increased delocalised electrons in metallics structure) then drops suddenly and decreases as molecules have less atoms so weaker intermolecular bonds
Negative ions with -1 charge
Nitrate no3
Hydroxide
Hydrogencarbonate
Ions with -2 charge
Sulphate
Carbonate
Ions with + charge
Ammonium
Ions with +2 charge
Copper
Zinc
Iron (ii)
Ion with +3 charge
Iron 3
What happens and what is the trend when group 2 metals react with water?
Form metal hydroxides and hydrgen
Increasing reactivity down group as outer electrons are more easily lost
What hapens when group 2 metals react with oxygen?
For metal oxides
What is the trend in thermal stability of group 2 carbonates?
Increased stability down group
The ions have lower charge density so less distortion
What is the trend in solubility of group 2 hydroxides?
Increase in solubility down the group
What is the trend in solubility of group 2 carbonates?
Decreases down group
Define ionisation ebthalpy?
The entgalpy needed to remove the 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous ions
What is the trend in ionisation enthalpues and why?
Increase across the period
And decreases down group
Atomic radius decreases
Nuclear charge Increases
Electron shielding
Solubility of nitrates?
Soluble
Sulfates are soluble except?
Barium
Calcium
Lead
Solubility of carbonates?
Insoluble except lithium potassium sodium and ammonium
Solubility of hydroxides?
Insoluble expect lithium sodium potassium strontium calcium barium and ammonium
Test for calcium?
White precipitate with sodium hydroxide
Test for copper?
Blue precipitate with sodium hydroxide
Test for iron (ii)?
Green precipitate with sodium hydroxides
Test for iron (iii)?
Brown precipitate with sodium hydroxide
Test for aluminium?
White dissolvable precipitate with sodium hydroxide
Test for carbonates?
HCl forms co2 so turns lime water cloudy
Test for sulfates?
Barium chloride
Forms a white precipitate
Test for ammonia
Litmus paper
Red- blue
Test for halides?
Add silver nitrate
White
Cream
Yellow
What happens when you add group 2 oxides and hydroxides to water?
They form alkaline solutions
Oxides form stronger alkalines down the group
Group 2 hydroxides/oxides and acids?
Neutralisation
What is the order of the electromagnetic spectrum?
Infrared visible ultraviolet
What is the melting point, solubility in water and conductivity like for giant ionic?
High melting point
Most soluble except: ba, ca, pb ag sulphate
Ag+ pb halides
Carbonates
Hydroxides (except g1 and nh4)
Conduct when in solution of molten
What is the melting point, solubility in water and conductivity of giant metallic structures?
High melting point
Insoluble in water, some react
Conductive when solid or liquid
What is the melting point, solubility in water and conductivity I’d giant covalent ?
Very high melting point
Insoluble
Unconductive - except graphite
What is the melting point, solubility in water and conductivity of simple covalent?
Low melting point
Insoluble unless the have polar group
Inconductive
What is an acid?
Has the ability to transfer H+
What is a base?
Has ability to accept H+ ions
What is an alkali?
Base that dissolved in water to produce hydroxide ions
What do solid and dashed wedges mean?
Solid wedges coming out of plane of paper, dashed are going behind
Define activation energy
The minimum energy needed in a collision to cause a reaction
What is meant by the term mole?
The amount of substance that has the same number of particles as there are atoms in 12g of carbon 12
What is an salt?
A compound where a H+ in an acid has been replaced by a metal ion
What is relative isotopic mass?
The mass of the atom compared to 1/12 th of the mass of carbon 12
describe the appearance and origin of the emission spectrum of the sun and explain how the lines can be used to identify elements
Appearance and origin • atoms absorb energy • electrons move up energy levels • energy levels quantised • (electrons) drop back down • emit light • ∆E = hv • give coloured lines
How lines can be used
• atoms of each element have their own specific
energy levels
• thus different gaps
• thus different frequency lines
• frequencies of lines can be checked against a
database
what is charge density?
the ratio of charge on an ion to its volume
