Different forms of the same element, with same number of protons but different number of neutrons.
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How do you work out relative atomic mass?
Sum of (isotope amount x isotope mass number) /sum of amount of all isotopes.
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What is a compound?
A substance formed from two or more elements, the atoms held together by chemical bonds.
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How did John Dalton describe atoms in the 19th century?
Solid spheres, different spheres making up the different elements.
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What did JJ Thompson conclude from his experiments in 1897?
Atoms weren't solid spheres as his measurements of charge and showed that atoms are positively charged 'puddings' that contain smaller electrons. This was called the PLUM PUDDING MODEL.
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What were the results of Rutherford 'Alpha particle scattering experiment' in 1909? What did these show?
Firing positively charged alpha particles at a thin sheet of gold showed that some particles went straight through, many were slightly deflected, some completely. Showing that the Atom had a solid nucleus, empty space & scattered electrons
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How and why did Bohr change the Nuclear Model?
If it was a 'cloud' around the nucleus, electrons would be attracted to the nucleus and it would collapse. Bohr suggested that electrons orbited the nucleus in fixed shells.
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What did James Chadwick discover?
Neutral particles in the nucleus, neutrons.
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In the early 1800's, how were elements arranged in the periodic table?
By atomic mass.
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What did Dmitri Mendeleev do in 1869?
Left gaps for new elements and arranged elements via atomic mass but also properties.
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What does the group number in the periodic table tell you? And what is the trend in reactivity?
How many electrons are in the elements outer shell. The trend in reactivity is group 1 reacting more vigorously as you proceed down the group, however this is opposite for group 7.
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What are the similar properties of metals?
Similar because they have metallic bonding; Strong but malleable, conduct heat and electricity, have a high boiling and melting points.
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Transition metals are in the centre of the table, what are their properties?
Good conductors, dense, strong, shiny. They have more than one ion (e.g. Copper; Cu+ and Cu2+) and are often coloured (e.g. potassium chromate VI). They make good catalysts (e.g. Nickel based).
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What are the properties of group 1 elements/Alkali metals?
Very reactive (e.g. with O2 and H2O). Low density, strength and melting points.
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How do the reactivity of Alkali metals increase further down the group?
Outer electron is more easily lost as attraction between nucleus and electron decreases as they're further away from each other as you go down the table.
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How do Alkali metals form ionic compounds with non-metals?
So easy for them to lose outer electron, not much energy needed. So they readily form ionic compounds, their compound is while solid that dissolves to colourless solution.
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How do Group 1 metals react with water?
Vigorously, to produce hydrogen gas and metal hydroxide - salts that dissolve in water to produce alkaline solutions. Energy released increases further down the table.
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How do Group 1 metals react with chlorine?
Vigorously, when heated in it's gas to produce white metal chloride salts.
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How do Group 1 metals react with oxygen?
Different types of oxide will form depending on the metal. Lithium forms lithium oxide, potassium forms potassium peroxide and superoxide etc.
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What are the coloured vapours of the following halogens; Fluorine, chlorine, bromine, iodine.
Halogens become less reactive, higher melting and boiling points, higher relative atomic masses.
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What happens when Halogens bond with metals?
They form 1- ions called Halides that have ionic structures
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What is a displacement reaction? (with Halogens)
Occur between a more reactive halogen and the salt of a less reactive one, which is replaces. E.g. Bromine displaces iodine due to the trend in reactivity.
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What are the properties of Group 0 elements/ Noble gases?
Full outer shells (apart from helium), barely reactive, stable, colourless at room temp, non-flammable.
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What is the pattern of the increasing boiling points down the noble gases?
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