Patterns in the properties of elements Flashcards
How is the Periodic table arranged?
Into groups and periods, in order of their proton number, this allows patterns to be found from their relative atomic masses and properties
What did Dobereiner discover?
He noticed ‘triads’ linking the RAM for three elements
What did Newlands discover?
He noticed ‘octaves’ where every eighth element had similar properties?
How did attitudes to early models of the periodic table develop?
At first Mendeleev’s table with gaps and predictions, Newlands’ triads and Dobreiner’s octaves were dismissed but when new elements were discovered that fit the patterns they were accepted
What are the group 1 metals and how do they react when cut?
Lithium, sodium, potassium are group 1 metals, when alkali metals are cut they are shiny at first then quickly tarnish in moist air due to reactions with oxygen.
What happens when alkali metals react with water?
They form hydrogen and an alkali solution of a hydroxide with the formula MOH
What happens when alkali metals react with chlorine?
They react vigorously to form colourless, crystalline salts with
the formula MCl
What trends are there in group 1 reactions with water?
As you go down the group they react with water more violently and vigorously
What are the main hazard symbols?
Highly flammable(big flame), toxic(skull and cross bones), corrosive (chemicals corroding), harmful(big x), explosive (explosion), oxidising(empty circle on fire)
What state and colour are halogens (group 7) at room temp and what colour as gases?
Chlorine is a pale green gas, bromine is a red-brown liquid and iodine a dark grey solid. As a gas chlorine is pale green, bromine reddish-brown, iodine purple
What is notable about all halogen molecules?
They are all diatomic, have 2 atoms joined together
What trends are there in group 7 in terms of reactivity?
As you go up the group they become more and more reactive
How does this reactivity affect their displacement of each other?
A displacement happens within a reaction when a more reactive (higher) halogen takes the place of a less reactive (lower) halogen.
How many electrons are in the outer shell of all group 1 metals?
1 electron in the outer shell, so form positive ions
How many electrons are in the outer shell of all group 7 metals?
7 electrons in the outer shell, so form negative ions
