C2 - The Periodic Table Flashcards
How did John Dalton arrange his periodic table?
Dalton arranged the elements in order of atomic weight in his book ‘a new system of chemical philosophy’.
John Newlands’ contribution the periodic table
He then built on John Daltons ideas and composed a law of octaves – every eighth element has similar properties, but he assumed that all elements had been found so in some places the pattern didn’t work at all. Other scientists ridiculed his ideas and refused to accept them.
Dimitri Mendeleev’s contribution to the periodic table
ordered the elements in order of atomic weight in a periodic (regularly occurring) pattern, leaving gaps for undiscovered elements. His table was fully accepted when the newly found elements fit with his predictions he made using his table.
Properties of metals
- conduct electricity
- high mpt and bpt,
- ductile
- malleable
- also on the left of the
‘stair case’
Properties of non-metals
- insulators
- low mpt and bpt
- not ductile
- brittle
- also on the right of the ‘stair cas’
Group 0 elements
Noble gases
- unreactive because their atoms have a stable arrangements of electrons
- monoatomic
- going down the group: bpt gets higher
Group 1 elements properties
The alkali metals
- all have 1 electron in their highest energy level
- low density
- stored in oil to prevent them from reacting with oxygen or water
Group 1 Reaction with water
- react with water releasing hydrogen to from hyrdroxide which dissolve in water to give alkaline solution
lithium = reacts slowly and fizzes
sodium = fizzes into a silver ball and moves around on the surface of the water.
potassium = pink or purple flame and fizzes
Reactions and Reactivity Trend of Group 1
- Group 1 metals react in a similar way as they all have 1 electron in their outer shell
- react with non-metals to form ionic compounds in which the metal ion carries a charge of + 1. The compounds are white solids which dissolve in water to form colourless solutions
Trend:
the further down the group an element is the more vigorously reactive it becomes as the atoms get larger the outer electrons are further from the nucleus and thus less attracted to the nucleus and so can more easily lose electrons
Group 7 properties
Halogens
- toxic non-metals that have coloured vapours
- all have 7 electrons in their highest energy levels
- diatomic
- form ionic salts with metals
- form molecular (simple covalent compounds with other non-metals
Trends in Group 7
Going down:
- higher relative atomic mass
- higher mpt and bpt
- the less reactive the element as the atoms get bigger, electrons are further from nucleus and less strongly attracted so it can less easily gain electrons.
Displacement Reactions
A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
Changes depending on which halogen
What happens as an atom gets larger
As an atom gets larger, electrons become easier to lose and harder to gain as there is less electrostatic attraction. Larger atoms lose electrons more easily because the outer electrons are further from the attractive force of the nucleus (which is positive). However large atoms gain electrons less easily because the inner electrons shield the positive electrostatic attraction of the nucleus which pull the electrons in.
Transition elements properties
Physical: - good conductors - hard - strong - high density - high mpt and bpt except mercury Chemical: - less reactive - don't react vigorously with oxygen, chlorine or water - corrode very slowly useful in industry as catalysts
many form coloured compounds.
can form more than one compound. e.g. Iron(II) and Iron (III) / ions with different charges
