How many elements were known in 1800?
What is relative atomic mass?
It is the mass of an element compared to the lightest element hydrogen
who formulated the idea of the modern periodic table?
- he listed elements in order of relative atomic mass, and also left gaps for undiscovered elements in his table. He also noticed that at intervals along the ordered elements were elements with similsr properties e.g. lithium, sodium,potassium share properties
What is the modern periodic table?
What is a general formula equation for group 1 elements reacting with chlorine and how does this reaction occur
-alkali metal +chlorine=salt
the matl burns in the gas producing different colured lights
-leaves colourless precipitate(salt)
What are some compounds of alkali metals?
sodium hydroxide(oven cleaner)
bicarbonate of soda, used in baking
Why are Group 1 metals called alkali meatl?and what are their properties?
as they leave an alkali solution when reacting with water
-corrosive, highly flammable
-reacts with air so kept in oil
-less dense then normal metals
What is the foemula equation for an alkali metal reacting with water?
alkali metal+water=hydrogen+an alkali metal hydroxide
What happens to the reactivity of metal as you go down the period in Group 1
What are the properties of Group 7 elements?
-all very reactive non-metals
-known as halogens
low melting point , high boiling point
forces between molecules is weak
melting and boiling points as yo go down the table
What are the properties of chlorine,Bromine and iodine?
What are some uses of halogens?
chlorine is used as bleach
florine is toothpaste
iodine to clean wounds
What happens to reactivity of halogens as you go up the periods?
What is a displacement reaction?
This where a more reactive halogen replaces the other halogen to form a new compound
HoW can unknown elements be identified?
By burning them and seeing the flame they produce
What was Dalton's theory about atoms?
every element has its own atoms that differ in mass
no atom can be created or destroyed
How many electrons can each shell hold?
What is a general rule to tell if a element is a metal or not?
elements with more than two electrons are generally gases
otherwise they are metals
What are some ions in the periodic table?