The Atom part 2

Question 1

• what takes up most of the atoms volume

Answer 1

the orbitals take up most of the volume of the atom

Question 2

• what did Jhon Dalton describe atoms as

Answer 2

at the start of the 19th century john Dalton described atoms as solid spheres, and said that different spheres made up the different elements

Question 3

• when was the electron discovered and who discovered it

Answer 3

in 1897 J. J. Thomson discovered the electron.

Question 4

• what did the plum pudding model show

Answer 4

this showed that atoms weren’t solid and indivisible

Question 5

• who conducted the gold foil experiment and when

Answer 5

in 1909 Ernest rutherford and his students Hans geiger and Ernest Marsden conducted their famous gold foil experiment.

Question 6

• what did they do in the gold foil experiment

Answer 6

they fired positively charged alpha particles at a very thin sheet of gold.

the plum pudding model suggested that most of the alpha particles would be slightly deflected by the positive nuclues 

however most past straight through 

so the plum pudding model was incorrect so rutherford developed the nuclear model

Question 7

• what did neils bohr propose after the nuclear model was discovered

Answer 7

neils bohr proposed a new model of the atom where electrons exist in shells or orbits of fixed energy

Question 8

• explain what happens when electrons move between shells

Answer 8

when electrons move between shells, electromagnetic radiation (with fixed energy or frequency) is emitted or absorbed.

the bohr model fitted experimental observations of the radiation emitted and absorbed by atoms

Question 9

• what did scienctists discover after bohr? Explain what this means.

Answer 9

scientists later discovered that not all the electrons in a shell have the same energy. this meant that the bohr model was not right. so they refined it to include sub-shells.

Question 10

• why is the refined Bohr model useful

Answer 10

becuase its simple and explains many experimental observations, like bonding and ionisation trends

Question 11

• what did glibert lewis discover

Answer 11

the inertnes of the noble gases was related to their having full outer shells of electrons

ions were formed by atoms losing or gaining electrons to attain full outer shells 

atoms could also bond by sharing electrons to form full outer shells

Question 12

• what can Daltons model be used to explain

Answer 12

the geometries of crystals

Question 13

• what can Bohrs model be used for

Answer 13

a simple model of ionic and covalent bonding

Question 14

• what can the charge cloud idea be used for

Answer 14

a more sophisticated explanation of bonding and the shapes of molecules

Question 15

• what can the simple model of electrons be used for

Answer 15

the simple model of electrons orbating in shells is useful for many purposes, particularly for working out bonding between atoms

Question 16

• what is the equation for the number of electrons in each shell

Answer 16

2n^2

n is the number of the shell

Question 17

• how many electrons can the first three shells hold up

Answer 17

the first shell holds up 2 electrons

the second hell holds up to eight electrons 

the third shell holds up to 18 electrons