GCSE Chemistry Flashcards
What was the gold foil experiment
The gold foil experiment was an experiment where alpha particles were fired at a sheet of gold foil , when some the alpha particles (positive particles) deflected back it proved that the plum pudding theory was wrong because it meant that the nucleus had to an area of dense positive charge rather than in the plum pudding model where the positive charge was so spread out that it couldn’t repel the positive alpha particles
What was the plum pudding model
The plum pudding was a model that suggested that the atom was a ball o positive charge with negative charge dotted in between.
What was the nuclear model
The nuclear model was a model that suggested that the atom had a positively charged nucleus with a cloud of electron surrounding it
Why did dimitri mendeleev leave gaps in his periodic table
He left gaps in his periodic table so that all elements with similar properties stayed in the same groups . The gaps indicated the existence of undiscovered elements .He allowed himself to predict the elements
How do group 1 metals react with water
Group 1 metals react vigourusly with water . The further down the group you go the more reactive the elements become because the vaillance electrons are further away and there is shell sheilding from the nucleus from the nucleus so have less of an attraction ao can easily react with other compounds such as water
Explain the full history of the periodic table
In 1803 John Dalton arranged the known elements in order of their respective weights . Then in 1817 Johann Wolfgang doberierner attempted to organise elements by putting them in groups . In 1862 Alex Emile noticed that elements with similar properties occurred regularly but didn’t use correct scientific terms or diagrams so was largely ignored . In 1865 John Newlands that when elements were placed in order of atomic weights lots of similarities could be found between the elements . He produced a table called the “law of octaves “ then in 1969 Dimitri Mendeleev arranged known elements in order of increasing atomic weight and left gaps for elements that hadent been discoved and so that elements with similar properties could stay together
What are the properties of noble gasses
Noble gasses are very un reactive because they have a full outer shell of electrons and cannot form any ions .
What are the properties of halogens
Halogens exist as diatomic molecules and become less reactive because the distance from the nucleus becomes less . When they react the gain an electron to form a full outer shell so therefore have a 1- ion
What are the properties of alkali metals
Alkali metals become more reactive as you go down the group as the electron shells become further away from the nucleus . If they react with non metals they lose an electron to gain a full outer shell so therefore form 1+ ions
What is a displacement reaction
A Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element. ( in the halogens case displacing a more reactive halogen with the salt of a less reactive one)
How do group 1 metals react with water
As you go down group 1 the more reactive and violent the reactions become with water .
How do group 1 metals react with chlorine
Group 1 metals react vigourusly when heated in chlorine gas , as you go down the group the reactivity increases .
How did Mendeleev place elements
Mendeleev put the elements in order of atomic mass but did change some so that elements with similar properties could stay together
What is the word equation when sodium and water react and when sodium and chlorine react
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What are isotopes
Isotopes are two different forms of the same element with different amount of neutrons
