Atomic Structure and Model

Question 1

what did John Dalten say about atoms

Answer 1

• all matter is made of atoms
• atoms are indestrucible and cant be broken down
• atoms of an element are identical
• atoms are rearranged in a chemical reaction
• compunds = 2 or more different atoms chemically joining together

Question 2

how are atoms in different elements different

Answer 2

number of protons, neutrons and electrons

Question 3

why do atoms have an overall charge or charge of 0

Answer 3

because they have the same number of protons and electrons

Question 4

what ratio is the size of the nucleus to the atom

Answer 4

1 to 10,000

Question 5

what is the atomic number of an atom

Answer 5

number of protons which indicates number of electrons

Question 6

what is the mass number of an atom

Answer 6

protons and neutrons added up

Question 7

what is an isotope

Answer 7

element with same number of protons but different number of neutrons and mass number

Question 8

what is relative atomc mass

Answer 8

weighted average of the masses of an atom of the isotopes for an element

Question 9

how to work out relative atomic mass (Ar)

Answer 9

Ar = (mass1 X percentage1) + (mass2 x percentage2) / 100

Question 10

who was the second person to develop ideas about the atom and what did he say (with what model)

Answer 10

• JJ thompson
• discovered electrons and said that atoms are built up of smaller pieces
• plum pudding model suggested that for atoms to be neutral and have a positive charge (the pudding) they must have negatively charged particles

Question 11

who was the third person to develop ideas about the atom and what did he say

Answer 11

• Rutherford
• showed that atoms have a nucleus that included positive particles
• this was done with alpha particle scattering. the atom was a nuclear atom

Question 12

what is alpha particle scattering

Answer 12

experiment by rutherford that consisted of shooting alpha particle radiation at a sheet of gold and observing for any reactions between an opposite force

Question 13

how do deflection of alpha particles suggest a nucleus exists

Answer 13

some alpha particles bounced back and most changed direction, meaning a large opposing forces must have acted on them, so theres a concentrated positive charge in the atom deflecting them back

Question 14

what did the small deflections of the alpha particle suggest about the atom

Answer 14

suggests that it consists of alot of empty space, so there must be a nucleus

Question 15

who was the fourth person to develop ideas about he atom and what did he say

Answer 15

bohr further developed rutherfords nuclear atom model and proved that electrons are organised in shells surrounding the nucleus

Question 16

what does the development of the theory of the atomic structure show

Answer 16

how a theory may change if new evidence is found

Question 17

relative mass of an electron

Answer 17

0.0005

Question 18

how do isotopes impact the relative atomic mass of an element

Answer 18

if there is a lot of an isotope it will impact the average mass and therefore the elements atomic number

Question 19

what did the alpha particle scattering disprove and how

Answer 19

• the plum pudding model
• model suggests that the atom is mainly positive and its charged is spread out
• but the positive particles bouncing back means theres a concentrated positive charge

Question 20

what did rutherford describe the atom to look like

Answer 20

a tiny positive charge at the center where most of the mass is concentrated with a cloud of electrons surrounding the nucleus