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Flashcards in Structure Of The Atom Deck (17)
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1
Q

Give evidence for atoms.

A
  • Brownian motion

- The ability of kinetic theorey to explain properties of matter eg gas pressure, diffusion

2
Q

Give evidence for electrons. Explain the experiment.

A

Thermionic emission:

  • negative particles - electrons - released from cathode.
  • attracted to an anode and absorbed, forming a current in the circuit
  • Thomson found electrons were easily deflected a lot by a magnet, showing they were extremely light.
3
Q

Who proposed the plum pudding model, and what is the plum pudding model?

A
  • Thomson proposed the plum pudding model.

- The plum pudding model depicts negative electrons embedded in a positively charged material.

4
Q

How did Thomson come up with the Plum Pudding model - what did he realise?

A

Thomson realised that since atoms are neutral, if they contain negative electrons, they must also contain some positive part.

5
Q

What did Rutherford do in 1909 to investigate the scattering of alpha-particles and what part of the atom was discovered through this?

A
  • in 1909 Rutherford investigated the scattering of alpha-particles by firing them at thin metal foils, including gold.
  • he discovered the nucleus
6
Q

Describe Rutherford’s alpha particle scattering experiment

A

Rutherford’s alpha particle scattering experiment

  • A narrow beam of alpha-particles from a radium source hit a thin sheet of gold foil.
  • The detector had a glass screen covered with zinc sulphide.
  • Any alpha particle hitting the screen caused a flash of light which was seen through a microscope.
6
Q

Outline the results of Rutherford’s alpha particle scattering experiment (3 marks)

A
  • most a-particles passed straight through or deflected at very small angles
  • 1 in 8000 were deviated more than 90 degrees
  • some bounced straight back
8
Q

Which experiement did Rutherford discover the nucleus from?

A

Rutherford’s alpha particle scattering experiment

9
Q

What did Rutherford propose in 1911?

A

In 1911 Rutherford proposed that an atom has a positively charged core (nucleus) which contains most of the mass of the atom and is surrounded by orbiting electrons.

10
Q

Describe the Rutherford-Bohr model of the atom. How many electrons can fill each shell in an atom?

A

Electrons occupy only certain allowed orbits in the atom.

A nucleus is surrounded by shells filled by orbiting electrons.

The first shell holds 2 electrons. The second shell holds 8 electrons. The third shell holds 18 electrons.

11
Q

Give the location, relative mass and relative charge of a proton.

A

Proton.
Location - Nucleus
Relative mass - 1
Relative charge - +1

Note that mass and charge are measured in comparison with the proton.

12
Q

Give the location, relative mass and relative charge of a neutron.

A

Neutron
Location - nucleus
Relative mass - 1
Relative charge - 0

Note that mass and charge are measured in comparison with the proton.

13
Q

Give the location, relative mass and relative charge of an electron.

A

Electron
Location - shells, orbiting the nucleus
Relative mass - 1/1840
Relative charge - -1

Note that mass and charge are measured in comparison with the proton.

14
Q

Outline how a nucleus is represented. (Clue - A, Z, X)

A

X - chemical symbol for the element concerned
A - atomic mass number (number of protons and neutrons in the nucleus)
Z - atomic number (number of protons in the nucleus)

Structure is as shown below:
A
X
Z

15
Q

What is the definition of an isotope?

A

Isotopes are atoms with the same number of protons but different numbers of neutrons. They have the same Z (atomic number) but different A (atomic mass number).

Since they have atoms of the same atomic number they are atoms of the same element.

16
Q

What are the isotopes of hydrogen? How many particles are in each isotope?

A

A stable hydrogen atom is just hydrogen with 1p and 1n.

The isotopes of hydrogen are Deuterium and Tritium.

Deuterium contains 1 proton, 1 neutron and 1 electron. (Mass number 2, atomic number 1)

Tritium contains 1 proton, 2 neutrons and 1 electron. (Mass number 3, atomic number 1)

16
Q

What is an atomic mass unit?

A

1u = 1.6605x10-27kg

-27 is an indicie