Atomic models

Question 1

what was the geiger- Marsden experiment?

Answer 1

• the gold foil experiment
• aka Rutherford experiment
• alpha particles fired at thin sheet of gold foil
• some deflected through large angles which suggested existence of a positively charged nucleus
• most particles went straight through
• some bounced back
• atoms are mostly empty space have small, dense , positively charged nucleus

Question 2

what was the purpose of the geiger- Marsden experiment?

Answer 2

• to test the plum pudding model
• to understand structure of the atom further

Question 3

what is relative isotopic mass?

Answer 3

• the mass of an atom relevant to one twelfth of the mass of an atom of carbon-12

Question 4

what is relative atomic mass?

Answer 4

• weighted mean mass of an atom of an element, compared with 1/12th the mass of an atom of carbon-12

Question 5

what is mass spectrometry?

Answer 5

• a technique used to determine the relative abundance of isotopes of an element

Question 6

what is the relative abundance?

Answer 6

• the percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element

Question 7

what are ions?

Answer 7

• an atom or group of atoms with a charge since they have a different number of protons and electrons

Question 8

what does m/z stand for?

Answer 8

• mass/charge
• if the charge is 1+, then the m/z is the same as the particles mass

Question 9

what is nuclear fusion?

Answer 9

• reactions involving smaller nuclei joining together to make larger nuclei

Question 10

state Ancient Greeks atomic theories

Answer 10

• 2500 years ago
• Democritus and Leucippus
• keep cutting things in half you get to the point where you can’t cut it in half anymore ( atomos meaning uncuttable)
• thought that all matter was made of atomos that come in different shapes and sizes

Question 11

was the Ancient Greeks ideas followed, if not why?

Answer 11

• people didn’t take to these ides as influential philosopher Aristotle proposed his idea that salt had spikes and iron had hooks ( shapes of atoms)
  -proposed that everything was made out of different amounts of elements
• people focused more on Aristotle as he was more influential
• they couldn’t carry out experiments at the time and therefore it was just a lucky guess

Question 12

state John Daltons atomic theory

Answer 12

• 1808
• John dalton a British chemist
• first experiments that showed that things were made of tiny little particles
• atoms= tiny balls arranged in different combinations to make different things
• indivisible = can’t be cut smaller
• not believed at first

Question 13

state JJ Thomson’s atomic theory

Answer 13

• 1904
• plum pudding model
• discovered that atoms had electrons ( much smaller atoms)
• proved John Dalton wrong as atoms are divisible because they contain electrons
  -if you were to split an atom in half, you would see tiny electrons inside ( plum)
• was a positively charged atom ( pudding)

Question 14

state Ernest Rutherfords atomic theory

Answer 14

• 1911
• used gold foil experiment
• discovered that atoms have a nucleus where all of its positive charge is concentrated , disproved Thompson who thought this positive charge was everywhere