Periodic Tablle Flashcards
Displacement reaction
A Reaction in which a more reactive element takes the place of a less reactive element in a compound
What was Mendeleev’s periodic table arranged in
In order of increasing atomic mass
Elements with similar properties kept in groups
To achieve this, he used creative thought and left gaps for undiscovered elements
He predicted very accurately properties of other elements not yet discovered
Today’s model of the periodic table
There are more element’s in today’s periodic table/no spaces in it
Arranged in order of increasing atomic number
Today’s has the noble gases in it
There is a separate block/area for the transition metals which are group together
Differences between mendeleev’s and today’s
Mendeleev’s was arranged in order of increasing atomic mass, the modern is order of increasing atomic number
The modern has noble gases, Mendeleev’s didn’t as they haven’t been discovered
Todays has the transition metals BLOCK Mendeleev’s doesn’t
Todays has more elements in it / no spaces
Alkali metals
Why are they so reactiv
What is there density
Only 1 electron in thei outer shell
They only need to lose 1 electron to get a full outer shell and become stable
Alkali metals have a low density and lithium , sodium and potassium are less dense then water therefore when added to water the float on the surface
Safety precaution when adding alkali metals to water
Word equation
General balanced equation
Use small pieces of metal
Use a safety screen- prevent metal sparking out
Wear safety glasses handle with tweezers
Metal + water -> metal hydroxide + hydrogen
2M + 2H2O -> 2MOH + H2
General observations
Heat released
Moves across surface of water
Colourless solution produced
Bubbles
Metal disapears (k= quickly)
Na = melts into tiny ball, yellow flame
K = melts into tiny ball, lilac flame
What happens to reactivity as you go down the group (1)
What happens to group 1 metals when they react
Reactivity increases
As the group is descended the atoms get bigger
Outer shell electron gets further away from the positive nucleus
So easier to remove as the outer negative electron is less attracted by the positive nucleus
They lose their outer electron
They become an ion with a 1+ charge
M-> M^+ + e^-
Why do all group 1 metals react the same way
What colour are they in compounds
They all have 1 electron in their outer shell
So they all lose 1 electron when they react to form a 1+ ion
All compounds form white solids , when they are dissolved i solution they form colourless solution
Halogens
Are they toxic
State , state at room temperature and pressure and colour
1 fluorine
2 chlorine
3 bromine
4 iodine
Yes must be used in a fume cupboard
1 gas yellow
2 gas green
3 liquid red brown
4 solid grey
What 3 things happen as you go down group 7
What is Astatine like
Why are they so reactive
Melting point/ boiling point increases
Atom size increases
Reactivity deceases
Black solid
They have 7 outer electrons
They only need to gain 1 electron to get a full outer shell and become stable
Iodine
What can it do (process)
Colour as
Gas
Solid
Equation
SUBLIME change from a solid to a gas
Grey crystals
Purple vapour
I2 (s)—> I2 (g)
Test for chlorine
What term is used to describe a reaction in which a substance breaks down when heated
Put damp litmus paper in test tube
Paper turn red then bleaches
Thermal decomposition
What happens to reactivity as you go down group 7
What happens to the group 7 elements when they react
REACTIVITY DECREASES
As the group is descended, the atoms get bigger
Outer shell is further away from positive nucleus so more difficult to attract an electron
They change name from and ine to an ide
They gain 1 electron
They become an ion with a 1- charge
X + e- -> X- 9atom)
Halogens are diatomic so an ionic equation for molecule is
X2 =2e- —. 2X- (molecule)
What do all group 7 elements react the same way
Halogens displacement reactions
They all have 7 electrons in their outer shell
They all gain 1 electron when they react to form a 1- ion
A more reactive halogen will displace from solution of its compound
So , as reactivity decreases down the group fluorine can displace chloride ions, chlorine can displace bromide ions etc
Displacement reactions
Observation
Full equation
Ionic equation
Chlorine with potassium bromide
Colourless—> orange
Cl2 + 2KBr -> Br2 + 2KCl
Cl2 + 2Br- —> Br2 +2Cl-
Observation
Balanced equation
Ionic equation
Chlorine with potassium iodide
Colourless -> yellow
Cl2 + 2kL -> I2 + 2KCl
Cl2 + 2I- —> I2 - 2Cl-
Observation
Balanced equation
Ionic equation
Bromine with potassium iodide
Colourless —>yellow
Br2 + 2kI -> I2 + 2KBr
Br2 +2I- -> I2 + 2Br-
Halogen displacement method
Add 1cm3 of chlorine water to 2 test tubes
Add about same amount to potassium iodide to one, potassium bromide to other
Record any observations
Repeat with bromine water (potassium chloride and iodide)
Repeat with iodine (potassium chloride and bromide)
Noble gases
Why re they called both group 8 and 0
What are there properties
Define- inert
Why are they so unreactive
Uses of
1 He
2 Ne
3 Ar
Have 8 electrons in their outer shell or sometimes referred to as having 0 in their outer shell
Colourless, inert(unreactive) gases
Have 8 electrons in their outer shell (He only 2) so its already full so they don’t need to react to gain/lose any electron
1 balloons
2 lighting
3 lighting and welding
Why do boiling points increase as you go down group 0
Why are their boiling points low (why are they gases)
The van der walls forces get stronger as you go down the group, so more energy is needed to break apart forces between the atoms
They are non-metals and are monoatomic ( exist as depart particles not molecules)
This means they only have very weak van der walls forces between their atoms
These require very little energy to break apart atoms
The transition metals
Where are they placed
Common properties
Large block between group 2 and 3
Good conductors of heat and electricity
Malleable / ductile
High melting point
Usually hard and tough
High densities
Can form ions with different charges
Their compounds are often coloured
Colours of
Copper oxide
Copper(II) carbonate
Hydrated copper(II) sulfate
Copper(II) sales in solution
Black
Green
Blue
Blue
State density, melting point, reaction with water, colour in compound, charge of ions of
Alkali metals
Transition metals
Alkali metals , low,low very vigorous, white ,1+
Transition metals, high,high, slow, coloured, variable charges
