1.6 periodic table Flashcards
How is the periodic table divided up
S,p,d,f blocks
period
How many electron shells an atom has
Group
How many electrons in outer shell
Oxidation
Loss of electrons
reduction
Gain of electrons
Melting and boiling points trends
Generally increase from first to fourth element followed by a large decrease to the fifth element and a small general decrease to the with element. This is because bonding changes from metallic to giant covalent to simple molecular covalent.
Why does ionisation energy between nitrogen and oxygen drop in period 2
Electron is being removed from oxygen is in an electron pair so the electron is removed more easily due to repulsion between two electrons.
Group 2 reacting with water
X + 2H20 —- X(OH)2 + H2
X IS GROUP 2 ELEMENT
Why does first ionisation energy increase across a period?
- Atomic radius decreases
- Shielding remains the same
- Nuclear charge increases
Overall the increases nuclear attraction
Group 2 reacting with oxygen
2X + O2—— 2XO
Flame test colours
Barium -apple green
Calcium - brick red
Copper - green-blue
Lead - blue flashes
Lithium - crimson red
Sodium - yellow/orange
Potassium - lilac
Magnesium - white
Strontium - red
Caesium- blue violet
Trend in thermal stabilities of group 1 and 2 carbonates and hydroxides
Group 2 carbonates and hydroxides can be decomposed by heat.
They become more stable to heat as you descend down the group.
Trend in reactivity down group 1 and 2
More reactive as you go down
Trend in solubility of group 2 hydroxides and sulphATES
Solubility increases down the group 2 elements except mg(oh)2 is typically insoluble
Sulphates decrease down the group except in BaSO4
All group 2 nitrates are soluble
Why does melting and boiling points increase down group 7
molecules get bigger and the number of electron shells increase down the group,
this means there are more intermolecular forces to overcome during melting/boiling so more energy is required to change state.
Hydroxides (OH-)
Form when group 1 and 2 elements react with water
Why do halogens exist in different states as you go sown the group
Cl is gas at room temp
Bromine is liquid at room temp
Iodine is solid at room temp
Because they have different melting and boiling points.
As you go down the melting and boiling points increase.
Halogens and metals
Salt forms
Halide ion test
Add nitric acid to remove carbon atoms and add silver nitrate to see precipitate from silver halide.(white Cl-, cream Br-, yellow I-)
Why does reactivity decrease down halogens
atomic radius increases, sheilding increases so less nuclear attraction so less able to attract electrons due to size of atom.
This means oxidising power of halogens also decreases down group 7 because its harder for atom to gain an electron.
Uses of chloride and fluoride ions
Water treatment to kill dangerous bacteria and viruses such as cholera and typhoid.
Fluoride prevents tooth decay by strengthening tooth enamel and preventing cavity formation.
displacement reaction of halogens in terms of redox
