Structure Of The Atom

Question 1

Dalton

Answer 1

Theory of atoms

Question 2

Theory of atoms

Answer 2

• are small indivisible particles
• of an element are identical
• of different elements vary in mass
  Compounds contain 2/more -
• = atoms

Question 3

Crookes

Answer 3

Discovered electrons

• travel in straight lines
• negatively charged
• =cathode rays

Question 4

Stoney

Answer 4

Gave electrons its name

Question 5

Thomson

Answer 5

Charge to mass ratio of cathode rays/electrons

Plum pudding model
negative electrons scattered in a larger positive dough

Question 6

Milikan

Answer 6

Oil drop experiment

Allowed the charge of an atom be measured accurately

Question 7

Rutherford

Answer 7

Discovered the nucleus

Gold leaf experiment
Aimed radioactive particles at a thin gold foil

Question 8

Chadwick

Answer 8

Proved the existence of neutrons.

Question 9

The gold leaf experiment

Answer 9

Most a particles travel theough the foil undeflected=
the atom is mostly empty space

Some a particles are deflected at an angle= positive charge is in the nucleus

An a particle travels back from the foil= nucleus is small and dense

Question 10

Electrons

Answer 10

In atoms occupy energy levels outside the nucleus

Question 11

An energy level

Answer 11

Is a region of definite energy within the atom that electrons occupy

Question 12

Bohr’s theory/ emission and absorption of light

Answer 12

Electrons occupy Fixed energy levels
electrons occupy lowest available energy level (ground state)
electrons can move to higher levels if they gain energy (excited state)
excited states are unstable, electrons will return to the ground state

Each element gives a unique colour or set of colours because each element has a unique number of electrons and transitions between energy levels.

Question 13

Problems with bohr’s theory

Answer 13

Wave particle duality
Hiesenberg’s uncertainty principle
Sub-levels and orbitals

Question 14

Hiesenberg’s uncertainty principle

Answer 14

It is possible to know the position or velocity of an electron but not both at the same time

Question 15

De broglie

Answer 15

First proposed that electrons could be treated as waves

Question 16

Atomic orbital

Answer 16

Is a region where the probability of finding an electron is high

Question 17

Aufbau principle

Answer 17

Electron will occupy the lowest energy sub level of available

No more than two electrons can occupy the same orbital

Electrons occupy orbitals Singly where possible

Question 18

Mass spectrometer

Answer 18

It works on the principle that ions can be separated by mass while moving in a magnetic field

FW Aston

Xxx

Vaporisation-sample inlet contains a heater to vaporise non-gaseous samples

Ionisation-An electron gun produces a beam of high energy electrons .this beam can remove electrons from an atom to form an ion

acceleration-an electric field is used to accelerate the ions to high speeds

Separation- streams of ions are deflected sideways as they move through a magnetic field. Lighter ions are deflected more than heavy ones

Detection- an electric current is generated when ions strike the detector

Question 19

Atomic number Z

Answer 19

Number of protons this determines what the element is

Question 20

Mass number A

Answer 20

Number of protons plus the number of neutrons in an atom or isotope sometimes referred to as the nucleon number

Question 21

isotopes

Answer 21

Atoms of an element which have the same atomic number but different mass numbers due to different numbers of electrons.

Question 22

Bohr model

Answer 22

Nucleus contains protons and neutrons
Electrons orbit the nucleus on energy levels
First shell can hold two electrons
Second shell can hold eight electrons

Question 23

Rows or the periodic table

Answer 23

Number of shells

Question 24

Distance on a periodic table

Answer 24

Number of electrons on the last shell