Periodic Table Flashcards
What was John Newlands table called?
Law of octaves
Who created the first modern periodic table?
Dmitrti Mendeleev
Why did Mendeleevs table prove accurate?
He left gaps, which predicted undiscovered elements, and swapped order of some elements to fit the pattern
These undiscovered elements were predicted correct
What three differences are there between Mendeleevs table and the modern periodic table?
- more elements and groups (transition metals) in modern table
- modern periodic table is in order of atomic mass, rather than Mendeleevs in order of atomic number
- there is no group 0 in Mendeleevs table
What are the group 1 elements?
Commonly referred to as alkali metals
- lithium (Li)
- sodium (Na)
- potassium (K)
- rubidium (Rb)
- caesium (Cs)
How hard are the group 1 metals?
They are very soft, with lithium requiring a sharp knife, and getting progressively easier to cut further down the group
How dense are the group 1 metals?
Li, Na and K would float on water, Rb and Cs would sink
They get progressively denser going down the group
How do the melting and boiling points of group 1 metals compare to other metals and why?
Much lower melting points, and the further you go down the group, the lower the mp, as +ve ions get bigger, so weaker attraction, and bonds are easier to break
Why are group 1 metals kept in oil?
To prevent them from reacting with the air
They tarnish when exposed to air
What occurs when group one metals react with water?
- they float
- they move about on surface
- effervescence
- flame on all except Li
What substance is formed in this reaction and what is its pH?
Hydroxide (OH)
pH 13/14
How does reactivity of group 1 metals change as you go down the group?
- atoms get bigger further down group
- outer electron further from nucleus
- attraction from nucleus is weaker, so it is more easily lost
- therefore metals are more reactive further down the group
What features do all group 1 compounds have?
- all ionic
- all white
- all soluble in water
- all solutions are colourless
Are group 7 atoms (halogens) diatomic?
Yes
What Bond exists between halogen atoms in the pairs?
Covalent
Why does mp of halogens get HIGHER as you go DOWN the group?
Halogens exist as diatonic molecules, so as you go down group, the bond between the atoms gets stronger as the atoms are larger, so intermolecular forces are stronger and need more heat energy to break
What is formed when a halogen reacts with a metal, and what is this type of reaction called?
- a halide
- direct combination (the only product is the compound)
How does reactivity change in halogens as you go UP the group?
It is easier to gain an electron when atom is smaller due to greater force of attraction from the nucleus, so higher up the group is more reactive
How do you make ionic equations?
Separate equation into individual bits, and cancel out bits that are present on each side
What is the acronym for half equations?
OIL RIG
Oxidation is loss
Reduction is gain
How do you get an oxidation half equation from an ionic equation?
Work out the element that loses electrons, then wrote out just the bits of that element as an equation, and ‘- how many electrons it loses’ at the end
How do you get an reduction half equation from an ionic equation?
Find the element that has gained electrons, then write out just those bits as an equation, and ‘+ how many electrons it gained’ before the ->
What colour and state is fluorine at room temp?
Pale yellow
Gas
What colour and state is chlorine at room temp?
Pale green
Gas
What colour and state is bromine at room temp?
Brown
Liquid
What colour and state is Iodine at room temp?
Dark grey
Solid
What are the colours of group 7 vapours?
Fluorine: pale yellow
Chlorine: pale green
Bromine: red-brown
Iodine: purple
What is the test for chlorine gas?
Chlorine turns damp blue litmus paper red, then bleaches it
Why are noble gases/ group 8 unreactive?
They have a full outer shell of electrons
What state and colour are noble gases at room temp?
Colourless gases
How do boiling points and densities change going DOWN the group?
Higher boiling points and densities further down the group
Guys this is scary why can they have 18 electrons on an outer shell 😰
Scary stuff right
What are uses for noble gases?
Neon lamps
Airships
Breathing apparatus for diving
Welding
Sunbeds
Lasers
Fog lights
Strobes
Radiotherapy
What properties do transition metals have?
- most typical metal properties
- much less reactive
- good catalysts
- can form more than one type of ion
- form coloured compounds
