Atomic Structure and the Periodic Table (1+2)
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What was John Dalton’s model of the atom? and when was this?
atoms are solid spheres (different spheres made up the different elements) at the start of the 19th century
What was Rutherford’s model of the atom? and when was this?
the nuclear model - most of the atom is empty space, there is a tiny, positively charged nucleus at the centre (where most of the mass in concentrated), a ‘cloud’ of negative electrons surrounds this nucleus 1909
When were protons disovered? and by who?
1917 by Rutherford
What was Bohr’s model of the atom? and when was this?
the nuclear model (improved) - electrons can only orbit the nucleus in fixed shells and aren’t found anywhere in between, each shell has a fixed energy 1913
When were neutrons discovered? and by who?
1932 by James Chadwick
What is the relative mass of an electron?
0.0005
What is the radius of an atom?
1x10^-10 m
What is the radius of a nucleus? and what is this in comparison to the atom?
1x10^-14 m about 1/10 000 of the size of the atom
What is the atomic number?
the number of protons in an atom
What is the mass number?
the number of protons and neutrons in an atom
What are isotopes?
different forms of the same element these have the same number of protons but a different number of neutrons (so the same atomic number but a different mass number)
What is the relative atomic mass of an element?
the average mass of one atom of the element compared to 1/12 of the mass of one atom of carbon-12
What is the formula for relative atomic mass of an element? based on the abundance of different isotopes
(isotope1 abundance x isotope1 mass number) + (isotope2 abundance x isotope2 mass number) … / 100
How did Dmitri Mendeleev arrange the elements into his version of the Periodic Table? (4 steps) and in what year?
• First he sorted the elements into groups, based on their properties. • He realised that if he put the elements in order of atomic mass, a pattern appeared - he could put elements with similar chemical properties in columns. • A few elements seemed to end up in the wrong columns so he switched the order of the elements to keep those with the same properties in the same columns. • To keep elements with similar properties together, he also had to leave some gaps. in 1869
What are the rows called in the Periodic Table?
periods
How are metals and non-metals separated in the Periodic Table?
by a zig-zag line running from boron to astatine (hydrogen is a non-metal)